BY AND AMONG

Exhibit 10.24

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NOTE PURCHASE AGREEMENT

BY
AND
AMONG

USINTERNETWORKING, INC.

GROTECH PARTNERS V L.P.

SOUTHERN VENTURE FUND II, L.P.

VENROCK ASSOCIATES

VENROCK ASSOCIATES II, L.P.

SOUTHEASTERN TECHNOLOGY FUND, L.P.

AND

SIEBEL SYSTEMS, INC.

Dated as of December 16, 1998

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TABLE OF CONTENTS

Page

ARTICLE I. DEFINITIONS............................................................................................1

1.1. Definitions.........................................................................................1
1.2. Accounting Terms: Financial Statements..............................................................4
1.3. Knowledge Standard..................................................................................4
1.4. Other Defined Terms.................................................................................4

ARTICLE II. AUTHORIZATION OF NOTES; PURCHASE AND SALE OF NOTES; MAKING OF LOANS...................................5

2.1. Notes...............................................................................................5
2.2. Purchase and Sale of Notes..........................................................................5
2.3. Closing.............................................................................................5
2.4. The Loans...........................................................................................5
2.5. Fees and Expenses...................................................................................6

ARTICLE III. CONDITIONS TO THE OBLIGATION OF THE PURCHASERS TO PURCHASE THE NOTES.................................6

3.1. Representations and Warranties......................................................................6
3.2. Compliance with Terms and Conditions of this Agreement..............................................6
3.3. Delivery of Notes...................................................................................6
3.4. Closing Certificates................................................................................6
3.5. Secretary's Certificates............................................................................6
3.6. Documents...........................................................................................7
3.7. Purchase Permitted By Applicable Laws...............................................................7
3.8. Consents and Approvals..............................................................................7
3.9. No Material Judgment or Order.......................................................................7
3.10. Waiver of Rights...................................................................................7

ARTICLE IV. CONDITIONS TO THE OBLIGATION OF USI TO CLOSE..........................................................7

4.1. Representations and Warranties......................................................................8
4.2. Compliance with this Agreement......................................................................8
4.3. Issuance Permitted by Applicable Laws...............................................................8
4.4. Loans...............................................................................................8
4.5. Consents and Approvals..............................................................................8
4.6. No Material Judgment or Order.......................................................................8

ARTICLE V. REPRESENTATIONS AND WARRANTIES OF USI..................................................................8

5.1. Corporate Existence and Authority...................................................................9
5.2. Corporate Authorization; No Contravention...........................................................9

5.3. Governmental Authorization; Third Party Consents....................................................9
5.4. Binding Effect......................................................................................9
5.5. Capitalization......................................................................................9
5.6. Private Offering...................................................................................10
5.7. Litigation.........................................................................................10
5.8. Financial Statements...............................................................................10
5.9. Tax Matters........................................................................................11
5.10. Investment Company/Government Regulations.........................................................11
5.11. Broker's Finder's or Similar Fees.................................................................11
5.12. Labor Relations and Employee Matters..............................................................11
5.13. Employee Benefits Matters.........................................................................11
5.14. Outstanding Borrowings............................................................................12
5.15. Insurance Schedule................................................................................12
5.16. Solvency..........................................................................................12
5.17. No Other Agreements to Sell Assets or Capital Stock...............................................12
5.18. Compliance with Law...............................................................................12
5.19. Disclosure........................................................................................12

ARTICLE VI. REPRESENTATIONS AND WARRANTIES OF THE PURCHASERS.....................................................13

6.1. Partnership or Corporate Existence and Authority...................................................13
6.2. Organization; Authorization; No Contravention......................................................13
6.3. Binding Effect.....................................................................................13
6.4. Purchase for Own Account...........................................................................13
6.5. Financial Condition................................................................................14
6.6. Receipt of Information.............................................................................14
6.7. Broker's, Finder's or Similar Fees.................................................................14
6.8. Governmental Authorization: Third Party Consent....................................................14
6.9. Litigation.........................................................................................15

ARTICLE VII. COVENANTS OF USI WITH RESPECT TO THE PERIOD FOLLOWING THE CLOSING...................................15

7.1. Reservation of Shares..............................................................................15

ARTICLE VIII. INDEMNIFICATION....................................................................................15

8.1. Indemnification....................................................................................15
8.2. Notification.......................................................................................16

ARTICLE IX. MISCELLANEOUS........................................................................................17

9.1. Survival of Representations and Warranties.........................................................17
9.2. Notices............................................................................................17
9.3. Successors and Assigns.............................................................................19
9.4. Amendment and Waiver...............................................................................19
9.5. Counterparts.......................................................................................19
9.6. Headings...........................................................................................19

9.7. Governing Law......................................................................................19
9.8. Severability.......................................................................................19
9.9. Rules of Construction..............................................................................20
9.10. Entire Agreement..................................................................................20
9.11. Further Assurances................................................................................20
9.12. Publicity.........................................................................................20
9.13. Jurisdiction......................................................................................20
9.14. Waiver of Jury Trial..............................................................................21

NOTE PURCHASE AGREEMENT

THIS NOTE PURCHASE AGREEMENT (the "Agreement") is entered into
as of the 16th day of December, 1998, by and among USinternetworking, Inc., a
Delaware corporation ("USi"), Grotech Partners V L.P., a Delaware limited
partnership ("Grotech II"), Southern Venture Fund II, L.P., a Delaware limited
partnership ("Xxxxxx II"), Venrock Associates, a New York limited partnership
("Venrock"), Venrock Associates II, L.P., a New York limited partnership
("Venrock II"), Southeastern Technology Fund, L.P., a Delaware limited
partnership ("Southeastern"), and Siebel Systems, Inc., a Delaware corporation
("Siebel") (Grotech II, Xxxxxx II, Venrock, Venrock II, Southeastern and Siebel)
are referred to collectively herein as the "Purchasers" and individually as a
"Purchaser").

RECITALS:

A. USi and the purchasers desire to complete an equity
financing on substantially the terms set forth in the term sheet attached hereto
as Exhibit A (the "Financing")

B. In order to provide USi with necessary working capital
prior to the consummation of the Financing, upon the terms and subject to the
conditions set forth in this Agreement, USi proposes to issue and sell its
Convertible Promissory Notes (the "Notes") to the Purchasers and to obtain from
the Purchasers the loans as contemplated thereby.

C. The Purchasers desire to purchase from USi the Notes and to
make the Loans as contemplated thereby, as set forth on Schedule 1 hereto.

AGREEMENT

NOW, THEREFORE, in consideration of the mutual covenants and
agreements set forth herein and for good and valuable consideration, the receipt
and adequacy of which is hereby acknowledged, the parties hereto hereby agree as
follows:

ARTICLE I.
DEFINITIONS

1.1. DEFINITIONS.

As used in this Agreement, and unless the context requires a
different meaning, the following terms have the meanings indicated:

"AFFILIATE" means, with respect to any specified Person, any
Person that, directly or indirectly, controls, is controlled by, or is under
common control with, such specified Person, whether by contract, through one or
more intermediaries, or otherwise.

"BUSINESS" means the business of USi as conducted and planned
to be conducted on the date hereof.

"BUSINESS DAY" shall mean a day other than a Saturday or
Sunday or any federal

holiday.

"COMMISSION" means the Securities and Exchange Commission or
any similar agency then having jurisdiction to enforce the Securities Act (as
defined below).

"CONDITION OF USI" means the assets, business, properties,
operations, financial condition or prospects of USi.

"CONTRACTUAL OBLIGATION" means any contract or agreement by
which a person is bound or to which its assets are subject.

"CONVERSION SHARES" has the meaning assigned thereto in the
Notes.

"EMPLOYEE PLANS" means all benefits arrangements, pensions
plans or welfare plans adopted by USi for its employees.

"EMPLOYEE STOCK OPTION PLAN" means an employee stock option
plan adopted by the Compensation Committee of the Board of Directors of USi
providing for the issuance to certain employees of USi of options to purchase a
certain number of shares of USi Common Stock at a certain exercise price per
share; the total number of shares of USi Common Stock which may be issued under
such plan shall not exceed 6.5% of the total number of outstanding shares of
common stock calculated on a fully diluted basis, not including the options and
shares issuable or issued on exercise of options pursuant to the Employee Stock
Option Plan.

"EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission thereunder.

"GAAP" means United States generally accepted accounting
principles, in effect from time to time, consistently applied.

"GOVERNMENTAL AUTHORITY" means the government of any nation,
state, city, locality or other political subdivision of any thereof, any entity
exercising executive, legislative, judicial, regulatory or administrative
functions of or pertaining to government, and any corporation or other entity
owned or controlled, through stock or capital ownership or otherwise, by any of
the foregoing.

"INDEBTEDNESS" means, as to any Person: (a) all obligations,
whether or not contingent, of such Person for borrowed money (including, without
limitation, reimbursement and all other obligations with respect to surety
bonds, letters of credit and bankers' acceptances, whether or not matured), (1))
all obligations of such Person evidenced by notes, bonds, debentures or similar
instruments, (c) all obligations of such Person representing the balance of
deferred purchase price of property or services, except trade accounts payable
and accrued commercial or trade liabilities arising in the ordinary course of
business, (d) all interest rate and currency swaps, caps, collars and similar
agreements or hedging devices under which payments are obligated to be made by
such Person, whether periodically or upon the happening of a contingency, (e)
all indebtedness created or arising under any conditional sale or other title

retention agreement with respect to property acquired by such Person (even
though the rights and remedies of the seller or lender under such agreement in
the event of default are limited to repossession or sale of such property), (f)
all obligations of such Person under leases which have been or should be, in
accordance with GAAP, recorded as capital leases, (g) all indebtedness secured
by any Lien (other than Liens in favor of lessors under leases other than leases
included in clause (f)) on any property or asset owned or held by that Person
regardless of whether the indebtedness secured thereby shall have been assumed
by that Person or is non-recourse to the credit of that Person, and (h) all
Indebtedness of any other Person referred to in clauses (a) through (f) above,
guaranteed, directly or indirectly, by that Person.

"LIEN" means any mortgage, deed of trust, pledge,
hypothecation, assignment, encumbrance, lien (statutory or other) or other
security interest of any kind or nature whatsoever (excluding preferred stock or
equity related preferences) including, without limitation, those created by,
arising under or evidenced by any conditional sale or other title retention
agreement, the interest of a lessor under a capital lease obligation, or any
financing lease having substantially the same economic effect as any of the
foregoing.

"OUTSTANDING BORROWINGS" means as to any Person all
Indebtedness of such Person for borrowed money (including, without limitation,
reimbursement and all other obligations with respect to surety bonds, letters of
credit and bankers' acceptances, whether or not matured).

"PERSON" means any individual, firm, corporation, partnership,
trust, incorporated or unincorporated association, joint venture, joint stock
company, Governmental Authority or other entity of any kind, and shall include
any successor (by merger or otherwise) of such entity.

"REQUIREMENTS OF LAW" means, as to any Person, the provisions
of the Certificate of Incorporation and By-laws or other organizational or
governing documents of such Person, and any law, treaty, rule, regulation,
right, privilege, qualification, license or franchise, order, judgment, or
determination of an arbitrator or a court or other Governmental Authority, in
each case, applicable or binding upon such Person or any of its property or to
which such Person or any of its property is subject or applicable to any or all
of the transactions contemplated by or referred to in the Transaction Documents.

"SECURITIES ACT" means the Securities Act of 1933, as amended,
and the rules and regulations of the Commission thereunder.

"SHAREHOLDERS AGREEMENT" means the Shareholders' Agreement
between USi and its shareholders dated as of May 28, 1998, as amended.

"TRADING DAY" means any day on which any market in which the
applicable security is then traded and in which a Quoted Price may be
ascertained is open for business.

"TRANSACTION DOCUMENTS" means collectively, this Agreement and
the Notes.

"TRANSACTION EXPENSES" means any and all reasonable
out-of-pocket (i) legal

expenses incurred by the Purchasers in connection with the negotiation and
preparation of the Transaction Documents, the consummation of the transactions
contemplated thereby and preparation for any of the foregoing, including,
without limitation, travel expenses, reasonable fees, charges and disbursements
of counsel and any similar or related legal costs and legal expenses, provided,
however, that USi shall pay only for one primary counsel of Purchasers and for
the reasonable attorney fees of the individual counsel of each Purchaser
incurred by such counsel in reviewing the Transaction Documents, but only to the
extent that the use of such individual counsel is required by such Purchaser's
institutional policies and procedures; and (ii) other expenses incurred by the
Purchasers in connection with the negotiation, preparation and consummation of
the Transaction Documents and the transactions contemplated thereby.

"USi STOCK" means Common Stock, par value $.001 per share, of
USi, or any other capital stock of USi into which such stock is reclassified or
reconstituted.

1.2. ACCOUNTING TERMS: FINANCIAL STATEMENTS.

All accounting terms used herein not expressly defined in this
Agreement shall have the respective meanings given to them in accordance with
sound accounting practice. The term "sound accounting practice" shall mean such
accounting practice as, in the opinion of the independent certified public
accountants regularly retained by USi conforms at the time to GAAP applied on a
consistent basis except for changes with which such accountants concur.

1.3. KNOWLEDGE STANDARD.

When used herein, the phrase "to the knowledge of" any Person,
"to the best knowledge of" any Person or any similar phrase shall mean, (i) with
respect to any individual, the actual knowledge of such Person, (ii) with
respect to any corporation, the actual knowledge of the officers and directors
of such corporation and the knowledge of such facts that such persons should
have in the exercise of their duties after reasonable inquiry, and (iii) with
respect to a partnership, the actual knowledge of the officers and directors of
the general partner of such partnership and the knowledge of such facts that
such persons should have in the exercise of their duties after reasonable
inquiry.

1.4. OTHER DEFINED TERMS.

The following terms shall have the meanings specified in the
Sections set forth below:

Term Section

Actions 5.7

Closing Date 2.2

Closing 2.3

Dispute 9.8

Financing Recital A

Indemnified Party 8.2

Indemnifying Party 8.2

Liabilities 8.2

Notes Recital B

Purchasing Indemnified Party 8.1(a)

Purchasing Indemnifying Party 8.1(b)

Selling Indemnified Party 8.1(b)

Selling Indemnifying Party 8.1(a)

ARTICLE II.
AUTHORIZATION OF NOTES;
PURCHASE AND SALE OF NOTES;
MAKING OF LOANS

2.1. NOTES.

On or before the Closing Date, the Board of Directors of USi
will authorize the issuance and sale of the Notes as contemplated hereby,
including authorizing the issuance of Conversion Shares upon conversion of the
Notes.

2.2. PURCHASE AND SALE OF NOTES.

Upon the terms and subject to the conditions herein contained,
on December 16, 1998 or such other day as the parties may agree (the "Closing
Date"), USi shall issue to each of the Purchasers, and each Purchaser shall
acquire from USi, a note (a "Note" and, collectively, the "Notes") in the form
of Exhibit B hereto and in the principal amounts shown on Schedule 1 hereto.

2.3. CLOSING.

The closing of the sale to and purchase by the Purchasers of
the Notes (the "Closing") shall occur at 11 o'clock A.M., local time on the
Closing Date at the offices of USi, One USi Plaza, Annapolis, Maryland. At the
Closing, USi shall deliver to each Purchaser the Note being purchased by such
Purchaser, free and clear of any Liens of any nature whatsoever, registered in
such Purchaser's name.

2.4. THE LOANS.

Subject to the terms and conditions herein contained, at the
Closing each of the Purchasers shall make a loan to USi (by wire transfer of
immediately available funds) in the amount set forth opposite its name on
Schedule 1. The obligation of the Purchasers to purchase the Notes and to make
the loans shall be several and not joint or joint and several.

2.5. FEES AND EXPENSES.

Concurrently with or as promptly as practicable after the
Closing, USi shall reimburse the Purchasers for the Transaction Expenses, which
payment shall be made by wire transfer of immediately available funds to an
account or accounts designated by the Purchasers.

ARTICLE III.
CONDITIONS TO THE OBLIGATION OF THE
PURCHASERS TO PURCHASE THE NOTES

The obligation of each Purchaser to purchase its Note, to make
its loan and to perform any of its obligations hereunder (unless otherwise
specified) shall be subject to the satisfaction of the following conditions on
or before the Closing Date:

3.1. REPRESENTATIONS AND WARRANTIES.

The representations and warranties of USi contained in Section
5 hereof shall be true and correct in all material respects at and as of that
date, as if made at and as of such date.

3.2. COMPLIANCE WITH TERMS AND CONDITIONS OF THIS
AGREEMENT.

USi shall have performed and complied with all of the
agreements and conditions set forth herein that are required to be performed or
complied with by USi on or before that date.

3.3. DELIVERY OF NOTES.

USi shall have delivered to each Purchaser the Note to be
received by such Purchaser.

3.4. CLOSING CERTIFICATES.

USi shall have delivered to each Purchaser a certificate
executed by an authorized officer of USi certifying that the representations and
warranties of USi are true and correct in all material respects on and as of
that date, and that the conditions set forth in this Section 3 to be satisfied
by USi have been satisfied on and as of that date.

3.5. SECRETARY'S CERTIFICATES.

Each Purchaser shall have received a certificate from USi,
dated as of that date and signed by the Secretary or an Assistant Secretary of
USi, certifying that the attached copies of the Certificate of Incorporation and
By-laws of USi and resolutions of the Board of Directors of USi approving the
Transaction Documents and the transactions referred to therein, are all true,

complete and correct and remain unamended and in full force and effect.

3.6. DOCUMENTS.

Each Purchaser or one Purchaser on behalf of all Purchasers
shall have received true, complete and correct copies of such documents and such
other information as it may have reasonably requested in connection with or
relating to the sale of the Notes and the transactions required to be performed
by the Transaction Documents.

3.7. PURCHASE PERMITTED BY APPLICABLE LAWS.

The acquisition of and payment for the Notes to be acquired by
the Purchasers hereunder and the consummation of this Agreement (a) shall not be
prohibited by any Requirements of Law, and (b) shall not conflict with or be
prohibited by any Contractual Obligation of USi.

3.8. CONSENTS AND APPROVALS.

All requisite consents, exemptions, authorizations, or other
actions by, or notices to, or filings with, Governmental Authorities and other
Persons in respect of all Requirements of Law and with respect to Contractual
Obligations of USi necessary or required in connection with the execution,
delivery or performance by USi shall have been obtained and be in full force and
effect and all waiting periods shall have lapsed without extension or the
imposition of any conditions or restrictions.

3.9. NO MATERIAL JUDGMENT OR ORDER.

There shall not be any judgment or order of a court of
competent jurisdiction or any ruling of any Governmental Authority or any
condition imposed under any Requirement of Law which, in the reasonable judgment
of the Purchaser, would (i) prohibit the purchase of the Notes hereunder, (ii)
subject the Purchaser to any penalty if the Notes were to be purchased
hereunder, or (iii) question the validity or legality of the transactions
required to be performed under this Agreement.

3.10. WAIVER OF RIGHTS.

All antidilutive and pre-emptive rights of shareholders of USi
with respect to the issuance of the Notes and the Conversion Shares shall have
been waived.

ARTICLE IV.
CONDITIONS TO THE OBLIGATION OF
USI TO CLOSE

The obligation of USi to issue and sell the Notes and the
other obligations of USi hereunder shall be subject to the satisfaction of the
following conditions on or before the Closing

Date:

4.1. REPRESENTATIONS AND WARRANTIES.

The representations and warranties of the Purchasers contained
in Section 6 hereof shall be true and correct in all material respects at and as
of the Closing Date as if made at and as of such date.

4.2. COMPLIANCE WITH THIS AGREEMENT.

The Purchasers shall have performed and complied with all of
the agreements and conditions set forth herein that are required to be performed
or complied with by the Purchasers on or before the Closing Date.

4.3. ISSUANCE PERMITTED BY APPLICABLE LAWS.

The issuance of the Notes hereunder and the consummation of
this Agreement (a) shall not be prohibited by any Requirements of Law, and (b)
shall not conflict with or be prohibited by any Contractual Obligations of the
Purchaser.

4.4. LOANS.

The Purchasers shall have made the loans as set forth in
Section 2.4 hereof.

4.5. CONSENTS AND APPROVALS.

All consents, exemptions, authorizations, or other actions by,
or notices to, or filings with, Governmental Authorities and other Persons in
respect of all Requirements of Law and with respect to those material
Contractual Obligations of the Purchasers necessary or required in connection
with the execution, delivery or performance by each Purchaser shall have been
obtained and be in full force and effect and all waiting periods shall have
lapsed without extension or imposition of any conditions or restrictions.

4.6. NO MATERIAL JUDGMENT OR ORDER.

There shall not be any judgment or order of a court of
competent jurisdiction or any ruling of any Governmental Authority or any
condition imposed under any Requirements of Law which, in the reasonable
judgment of USi would (i) prohibit the sale of the Notes or the consummation of
the other transactions hereunder, (ii) subject USi to any penalty if the Notes
were to be sold hereunder or (iii) question the validity or legality of the
transactions required to be performed under this Agreement.

ARTICLE V.
REPRESENTATIONS AND WARRANTIES
OF USI

USi represents and warrants to, and covenants with, the
Purchasers as of the date

hereof and as of the Closing Date as follows:

5.1. CORPORATE EXISTENCE AND AUTHORITY.

USi was incorporated on January 14, 1998 and (a) is a
corporation duly organized, validly existing and in good standing under the laws
of the State of Delaware, (b) has all requisite corporate power and authority to
own and operate its property, to lease the property it operates as lessee and to
conduct the business in which it is currently, or is currently proposed to be,
engaged, and (c) has the corporate power and authority to execute, deliver and
perform its obligations under each Transaction Agreement to which it is or will
be a party.

5.2. CORPORATE AUTHORIZATION; NO CONTRAVENTION.

The execution, delivery and performance by USi of each of the
Transaction Documents and the consummation of the transactions contemplated
thereby, including, without limitation, the issuance of the Notes by USi, (a) on
or before the Closing Date, shall have been duly authorized by all necessary
corporate action, including the approval of the holders of two-thirds of the
outstanding Series A Convertible Preferred Stock of USi, do not conflict with or
contravene the terms of the Certificate or the Bylaws of USi, or any amendment
thereof; and (b) will not violate, conflict with or result in any material
breach or contravention of (i) any Contractual Obligation of USi or (ii) any
Requirements of Law applicable to USi.

5.3. GOVERNMENTAL AUTHORIZATION; THIRD PARTY CONSENTS.

No approval, consent, compliance, exemption, authorization, or
other action by, or notice to, or filing with, any Governmental Authority or any
other Person in respect of any applicable Requirements of Law in effect on the
date hereof and no lapse of a waiting period under any applicable Requirements
of Law in effect on the date hereof, is necessary or required in connection with
the execution and delivery of the Transaction Documents by USi or the
performance by USi or enforcement against USi of any material obligation by USi
under the Transaction Documents or the transactions to be performed hereunder.

5.4. BINDING EFFECT.

This Agreement has been duly executed and delivered by USi and
constitutes its legal, valid and binding obligation enforceable against it in
accordance with its terms, except as enforceability may be limited by applicable
bankruptcy, insolvency or other similar laws affecting the enforcement of
creditors' rights generally and by general principles of equity relating to
enforceability.

5.5. CAPITALIZATION.

(a) On the Closing Date, the authorized capital stock
of USi shall consist of three hundred million (300,000,000) shares of Common
Stock and two hundred

thousand (200,000) shares of preferred stock. Of the authorized shares of USi
Common Stock, immediately after the Closing, (i) ninety-nine million
(99,000,000) shares of Common Stock will be reserved for issuance upon
conversion of shares of the Series A Preferred Stock, (ii) six million, six
hundred thousand (6,600,000) shares of USi Common Stock will be reserved for
issuance pursuant to the Employee Stock Option Plan; (iii) up to nine million,
two hundred ninety thousand, nine hundred fifty seven (9,290,957) shares of USi
Common Stock will be reserved for issuance upon exercise of Common Stock
purchase warrants (the "Warrants"), and (iv) twenty million (20,000,000) shares
of Common Stock will be issued and outstanding. As of the Closing Date, all
outstanding shares of capital stock of USi will be duly authorized and validly
issued, fully paid, nonassessable and free and clear of any Liens, preferential
rights, priorities, claims, options, charges or other encumbrances or
restrictions other than those created by the Certificate of Incorporation and
the Bylaws of USi and the Shareholders' Agreement.

(b) SCHEDULE 5.5 sets forth the name of each holder
of the issued and outstanding capital stock of USi, the number of shares of such
capital stock held beneficially or of record by each such holder, the name of
each Person holding any options or other rights to purchase any capital stock of
USi (except as may be permitted under the Shareholders Agreement), the number,
class and series of shares of capital stock subject to each such option or right
and the exercise price of each such option or right. Except as set forth on
SCHEDULE 5.5, there are no outstanding securities convertible into or
exchangeable for capital stock of USi or options, warrants or other rights to
purchase or subscribe to capital stock of USi or contracts, commitments,
agreements, understandings or arrangements of any kind to which USi is a party
relating to the issuance of any capital stock of USi, any such convertible or
exchangeable securities or any such options, warrants or rights.

5.6. PRIVATE OFFERING.

No form of general solicitation or general advertising was
used by USi or its representatives in connection with the offer or sale of the
Notes. No registration of the Notes pursuant to the provisions of the Securities
Act or any state securities or "blue sky" laws will be required by the offer,
sale or issuance of the Notes pursuant to this Agreement. USi agrees that
neither it, nor anyone authorized to act on its behalf will offer or sell the
Notes or any other security so as to require the registration of the Notes
pursuant to the provisions of the Securities Act or any state securities or
"blue sky" laws, unless such Notes are so registered.

5.7. LITIGATION.

USi has not received any notice of any governmental charge,
complaint or action or court order, writ, injunction, judgment or decree
outstanding or any claim, suit, litigation, legal proceeding, (collectively,
"Actions") which if adversely determined would have a material adverse effect on
(i) the Condition of USi (ii) the transactions required to be performed by USi
under this Agreement or the Transaction Documents and, to USi's knowledge, there
is no valid basis therefor, and no Action is threatened against USi.

5.8. FINANCIAL STATEMENTS.

USi has delivered to the Purchasers its audited financial
statements as of June 30, 1998 and unaudited financials as of October 31, 1998
and for the period then ended. Such financial statements are true and complete
in all material respects and fairly present the financial condition and results
of operations of USi as of October 31, 1998 and for the period then ended in
accordance with generally accepted accounting principles. Since October 31, 1998
there has been no material adverse change in the business, financial condition,
operating results or prospects of USi. All of USi's material liabilities are
reflected in such financial statements or on SCHEDULE 5.8 attached hereto, other
than liabilities incurred in the ordinary course of business since October 31,
1998.

5.9. TAX MATTERS.

USi has duly filed all tax reports and returns required to be
filed by it, including all federal, state, local and foreign tax returns and
reports and paid all taxes due with respect thereto.

5.10. INVESTMENT COMPANY/GOVERNMENT REGULATIONS.

Immediately following the Closing, after giving effect to the
transactions contemplated by the Transaction Documents, neither USi nor any
Person controlling, controlled by or under common control with USi will be an
"investment company" within the meaning of the Investment Company Act of 1940,
as amended. USi is not subject to regulation under the Public Utility Holding
Company Act of 1935, as amended, the Federal Power Act, or any federal or state
statute or regulation limiting its ability to incur Indebtedness.

5.11. BROKER'S FINDER'S OR SIMILAR FEES.

There are no brokerage commissions, finder's fees or similar
fees or commissions payable in connection with the transactions contemplated
hereby based on any agreement, arrangement or understanding with USi or any
officer, director, shareholder, or Affiliate of USi or any action taken by any
such person.

5.12. LABOR RELATIONS AND EMPLOYEE MATTERS.

(a) USi is not and has not engaged in any unfair
labor practice.

(b) Except as set forth on SCHEDULE 5.12, USi is not
a party to any employment agreement (other than "at will" employment
relationships), collective bargaining agreement or covenant not to compete.

5.13. EMPLOYEE BENEFITS MATTERS.

Except as set forth on SCHEDULE 5.13, USi has not adopted or
implemented any Employee Plan.

5.14. OUTSTANDING BORROWINGS.

SCHEDULE 5.14 lists the amount of all Outstanding Borrowings
of USi as of the date hereof and the name of each lender thereof.

5.15. INSURANCE SCHEDULE.

USi maintains insurance policies with reputable insurers
covering such risks and in such amounts as are customary for similar businesses.

5.16. SOLVENCY.

USi has not (i) made a general assignment for the benefit of
its creditors, (ii) filed any voluntary petition in bankruptcy or suffered the
filing of any involuntary petition in bankruptcy by its creditors, (iii)
suffered the appointment of a receiver to take possession of all or
substantially all of its assets or properties, (iv) suffered the attachment or
other judicial seizure of all or substantially all of its assets or (v) admitted
in writing its inability to pay its debts as they come due.

5.17. NO OTHER AGREEMENTS TO SELL ASSETS OR CAPITAL STOCK.

Other than as otherwise set forth in this Agreement, USi has
no legal obligation, absolute or contingent, other than obligations under the
Transaction Documents, to any person or firm to (i) sell any of its capital
stock or, outside of the ordinary course of business, assets, or effect any
merger, consolidation or other reorganization or (ii) enter into any agreement
with respect to any of the foregoing.

5.18. COMPLIANCE WITH LAW.

In its conduct of its business and affairs since its
formation, USi has complied in all material respects with all applicable
Requirements of Law.

5.19. DISCLOSURE.

USi has, to the best of its knowledge, fully responded to all
requests for information, and each of USi has accurately answered all questions
from the Purchasers concerning the Condition of USi, and has not knowingly
withheld any facts relating thereto which it reasonably believes to be material
with respect to its Condition. No information in this Agreement or in any
Exhibit or Schedule attached to this Agreement, contains or will contain any
untrue statement of a material fact or when considered together with all such
information delivered to the Purchasers omits to state any material fact. The
disclosures made in writing by USi in connection with this Agreement when read
in the light of the circumstances when made and taken as a whole, did not when
made contain any untrue statement of a material fact.

ARTICLE VI.
REPRESENTATIONS AND
WARRANTIES OF THE PURCHASERS

Each Purchaser, severally and not jointly, hereby represents
and warrants to USi as of the date hereof as follows:

6.1. PARTNERSHIP OR CORPORATE EXISTENCE AND AUTHORITY.

As applicable, such Purchaser is either a limited partnership,
limited liability company, or corporation (a) duly organized, validly existing
and in good standing under the laws of the jurisdiction of its formation, (b)
has all requisite power and authority to own its assets and operate its
business, and (c) has all requisite power and authority to execute, deliver and
perform its obligations under each of the Transaction Documents to which it is
or will be a party.

6.2. ORGANIZATION; AUTHORIZATION; NO CONTRAVENTION.

The execution, delivery and performance by such Purchaser of
the Transaction Documents to which it is a party and the consummation of the
transactions contemplated thereby, including, without limitation, the
acquisition of the Notes: (a) is within such Purchaser's partnership, limited
liability company, or corporate power and authority, as applicable, and has been
duly authorized by all necessary action on the part of such Purchaser; does not
conflict with or contravene the terms of such Purchaser's charter or by-laws, as
applicable; and (c) will not violate, conflict with or result in any material
breach or contravention of (i) any Contractual Obligation of such Purchaser, or
(ii) the Requirements of Law or any order or decree applicable to such
Purchaser.

6.3. BINDING EFFECT.

This Agreement has been duly executed and delivered by such
Purchaser, and this Agreement constitutes the legal, valid and binding
obligation of such Purchaser, enforceable against it in accordance with its
terms, except as enforceability may be limited by applicable bankruptcy,
insolvency, or similar laws affecting the enforcement of creditors' rights
generally or by equitable principles relating to enforceability.

6.4. PURCHASE FOR OWN ACCOUNT.

The Notes and the Conversion Shares are being or will be
acquired by such Purchaser for its own account and with no intention of
distributing or reselling such securities or any part thereof in any transaction
that would be in violation of the securities laws of the United States of
America, or any state, without prejudice, however, to the rights of such
Purchaser at all times to sell or otherwise dispose of all or any part of such
stock under an effective registration statement under the Securities Act, or
under an exemption from such registration available under the Securities Act,
and subject, nevertheless, to the disposition of such Purchaser's property being
at all times within its control. If such Purchaser should in the future decide
to dispose of any of the Notes or Conversion Shares, such Purchaser understands
and agrees that it may do so only in compliance with the Securities Act and
applicable state securities laws, as then in effect. Such Purchaser agrees to
the imprinting, so long as required by law, of a legend on certificates
representing all of the Notes and Conversion Shares to the following effect:

"THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933. AS AMENDED. OR THE SECURITIES LAWS
OF ANY STATE AND MAY NOT BE SOLD OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES
LAWS OR PURSUANT TO AN APPLICABLE EXEMPTION TO THE REGISTRATION REQUIREMENTS OF
SUCH ACT OR SUCH LAWS. THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE
SUBJECT TO CERTAIN RESTRICTIONS SET FORTH IN A SHAREHOLDERS AGREEMENT DATED AS
OF MAY 28, 1998. A COPY OF SUCH AGREEMENT MAY BE OBTAINED FROM USi UPON REQUEST"

6.5. FINANCIAL CONDITION.

Such Purchaser's financial condition is such that it is able
to bear the risk of holding the Notes for an indefinite period of time and can
bear the loss of its entire investment in the Notes. Such Purchaser has such
knowledge and experience in financial and business matters and in making high
risk investments of this type that it is capable of evaluating the merits and
risks of the purchase of the Notes.

6.6. RECEIPT OF INFORMATION.

Such Purchaser has been furnished access to the business
records of USi and such additional information and documents as such Purchaser
has requested and has been afforded an opportunity to ask questions of and
receive answers from representatives of USi concerning the terms and condition
of this Agreement, the purchase of the Notes, the prospective operations, market
potential, capitalization, financial conditions, and prospects of the business
to be conducted by USi, and all other matters deemed relevant by such Purchaser.

6.7. BROKER'S, FINDER'S OR SIMILAR FEES.

There are no brokerage commissions, finder's fees or similar
fees or commissions payable in connection with the transactions contemplated
hereby based on any agreement, arrangement or understanding with such Purchaser
or any action taken by such Purchaser.

6.8. GOVERNMENTAL AUTHORIZATION: THIRD PARTY CONSENT.

No approval, consent, compliance, exemption, authorization, or
other action by, or notice to, or filing with, any Governmental Authority or any
other Person in respect of any Requirements of Law, and no lapse of a waiting
period under any Requirements of Law, is necessary or required in connection
with the execution, delivery or performance by such Purchaser (including,
without limitation, the acquisition of the Notes) or enforcement against such
Purchaser of this Agreement or the Other Transaction Documents to which it is a
party or the transactions contemplated thereby.

6.9. LITIGATION.

No Actions are pending, or to the best knowledge of such
Purchaser, threatened relating to or affecting the transactions required to be
performed by such Purchaser under the Transaction Documents.

ARTICLE VII.
COVENANTS OF USI WITH RESPECT
TO THE PERIOD FOLLOWING THE CLOSING

Until all Notes are no longer outstanding due to conversion or
otherwise and until the payment by USi of all other amounts due to the
Purchasers under the Transaction Documents, USi hereby covenants and agrees with
each Purchaser as follows:

7.1. RESERVATION OF SHARES.

When the Financing is authorized, the Company will reserve the
maximum number of Conversion Shares that may be issuable or deliverable upon
conversion of the Notes. The Conversion Shares shall, when issued or delivered
in accordance with the provisions of USi's Certificate of Incorporation, be duly
authorized, validly issued and fully paid and non-assessable. USi shall issue
such Conversion Shares in accordance with the provisions of its Certificate of
Incorporation and shall otherwise comply with the terms thereof.

ARTICLE VIII.
INDEMNIFICATION

8.1. INDEMNIFICATION.

(a) In addition to all other sums due hereunder or
provided for in this Agreement, USi (the "Selling Indemnifying Party") shall
defend, indemnify and hold harmless each Purchaser and its Affiliates and their
respective officers, directors, agents, employees, subsidiaries, partners and
assigns (each a "Purchasing Indemnified Party") to the fullest extent permitted
by law from and against any and all losses, costs, claims, damages, expenses
(including reasonable fees, disbursements and other charges of counsel, as
limited by Section 8.2 below) and other liabilities (collectively,
"Liabilities") incurred or suffered by any Purchasing Indemnified Party
resulting from or arising out of (i) any breach by any Selling Indemnifying
Party of any representation or warranty, covenant or agreement of the Selling
Indemnifying Party in this Agreement; provided, however, that no Selling
Indemnifying Party shall be liable under this Section 8.1 to any Purchasing
Indemnified Party to the extent that it is finally judicially determined that
such Liabilities resulted primarily from the material breach by such Purchasing
Indemnified Party of any representation, warranty, covenant or other agreement
of such Purchasing Indemnified Party contained in this Agreement; or (ii) any
material liability of USi on the Closing Date not disclosed in this Agreement.

(b) In addition to all other sums due hereunder or
provided for in this Agreement, each Purchaser (each a "Purchasing Indemnifying
Party"), severally and not jointly, shall defend, indemnify and hold harmless
USi and its Affiliates and its officers, directors, agents, employees,
subsidiaries, partners and assigns (each a "Selling Indemnified Party") to the

fullest extent permitted by law from and against any and all Liabilities
incurred or suffered by such Selling Indemnified Parties resulting from or
arising out of any breach of any representation, warranty, covenant or agreement
of such Purchasing Indemnifying Party in this Agreement; provided, however, that
no Purchasing Indemnifying Party shall be liable under this Section 8.1 to a
Selling Indemnified Party to the extent that it is finally judicially determined
that such Liabilities resulted primarily from the material breach by such
Selling Indemnified Party of any representation, warranty, covenant or other
agreement of such Selling Indemnified Party contained in this Agreement.

(c) If and to the extent that any indemnification
provided for in this Agreement is unenforceable for any reason, the Indemnifying
Parties (as defined below) obligated to indemnify any Indemnified Party (as
defined below) shall make the maximum contribution to the payment and
satisfaction of such indemnified liability which shall be permissible under
applicable laws. In connection with the obligation of the Indemnifying Parties
to indemnify for expenses as set forth herein, the Indemnifying Parties further
agree, upon presentation of appropriate invoices containing reasonable detail,
to reimburse each Indemnified Party for all such expenses (including reasonable
fees, disbursements and other charges of counsel, as limited by Section 8.2
below) as they are incurred by such Indemnified Party.

8.2. NOTIFICATION.

If any action or proceeding (including any governmental
investigation or inquiry) shall be brought or asserted against any party
entitled to indemnification pursuant to this Section 8 (an "Indemnified Party")
in respect of which indemnity may be sought from any party required to indemnify
such Indemnified Party (an "Indemnifying Party"), such Indemnified Party shall
promptly notify the Indemnifying Party in writing, and such Indemnifying Party
shall assume the defense thereof, including the employment of counsel selected
by such Indemnifying Party and reasonably satisfactory to such Indemnified Party
and the payment of all expenses; provided, however, that any failure to so
notify such Indemnifying Party shall not impair obligations hereunder except if
and only to the extent that such failure results in actual prejudice to such
Indemnifying Party. Such Indemnified Party shall have the right to employ
separate counsel in any such action and to participate in the defense thereof,
but the fees and expenses of such counsel shall be the expense of such
Indemnified Party unless (a) such Indemnifying Party agreed to pay such fees and
expenses or (b) such Indemnifying Party shall have failed to assume the defense
of such action or proceeding or has failed to employ counsel reasonably
satisfactory to such Indemnified Party in any such action or proceeding or (c)
the named parties to any such action or proceeding (including any impleaded
parties) include both such Indemnified Party and such Indemnifying Party, and
such Indemnified Party shall have been advised by counsel that there may be one
or more legal defenses available to such Indemnified Party which are different
from or additional to those available to such Indemnifying Party (in which case,
such Indemnifying Party shall employ separate counsel at the expense of such
Indemnifying Party, it being understood, however, that such Indemnifying Party
shall not, in connection with any one such action or proceeding or separate but
substantially similar or related actions or proceedings in the same jurisdiction
arising out of the same general allegations or circumstances, be liable for the
reasonable fees and expenses of more than one separate firm of attorneys at any
time for such

Indemnified Party and any other Indemnified Parties). No Indemnifying Party
shall be liable for any settlement of any such action or proceeding effected
without its written consent (which shall not be withheld unreasonably), but if
settled with its written consent, or if there be a final judgment for the
plaintiff in any such action or proceeding, such Indemnifying Parry agrees to
indemnify and hold harmless such Indemnified Party from and against any
Liabilities by reason of such settlement or judgment. No Indemnifying Party
shall agree to any settlement of any third party claim without the consent of
the Indemnified Party, which shall not be withheld if such settlement provides
only for the payment of money to be paid by the Indemnifying Party.

ARTICLE IX.
MISCELLANEOUS

9.1. SURVIVAL OF REPRESENTATIONS AND WARRANTIES.

All of the representations and warranties made herein shall
survive the Closing.

9.2. NOTICES.

All notices, demands and other communications provided for or
permitted hereunder shall be made in writing and shall be by registered or
certified first-class mail, return receipt requested, courier service or
personal delivery or via facsimile:

(a) if to Purchasers:

If to Grotech II:
Grotech Capital Group
0000 Xxxxxxx Xxxx
Xxxxxxxx, XX 00000
Attention: Xxxxx X. Xxxxx

If to Xxxxxx II:
Xxxxxx Xxxxx Capital Corporation
000 00xx Xxxxxx Xxxxx
Xxxxxxxxx, XX 00000
Attention: Xxxxxxx X. Xxxxxxxx

If to Venrock or Venrock II:
Venrock Associates
Room 5506
00 Xxxxxxxxxxx Xxxxx
Xxx Xxxx, XX 00000
Attention: Xxx X. Xxxxxxxx

with a copy to:

Xxxx, Stettinius & Hollister LLP
1800 Star Bank Center
000 Xxxxxx Xxxxxx
Xxxxxxxxxx, Xxxx 00000
Attention: Xxxxxx X. Xxxxxxxxx, Esq.

If to Southeastern:

Southeastern Technology Fund, L.P.

0000 Xxxxxxxx Xxxxxxx Xxxxx

Xxxxxxxxxx, Xxxxxxx 00000

Attention: Xxxxx Xxxxxx, Chairman

If to Siebel:

Siebel Systems, Inc.
0000 X. Xxxxx Xx.
Xxx Xxxxx, Xxxxxxxxxx 00000
Attention: Xxxxxxx Xxxxx

(b) if to USi:

USinternetworking, Inc.
One USi Plaza
000 Xxxxxxx Xxxxxxxx Xxxxx
Xxxxx 000
Xxxxxxxxx, Xxxxxxxx 00000
Attention: Xxxxxxxxxxx X. XxXxxxxx

with a copy to:

Xxxxxx & Xxxxxxx
0000 Xxxxxxxxxxxx Xxxxxx, X.X.
Xxxxx 0000
Xxxxxxxxxx, X.X. 00000-0000
Attention: Xxxxx X. Xxxxxx, Esq.

All such notices and communications shall be deemed to have been duly given:
when delivered by hand, if personally delivered; when delivered by courier, if
delivered by commercial overnight courier service; if delivered by facsimile,
upon confirmation of such transmission; and five business days after being
deposited in the mail, postage prepaid, if mailed.

9.3. SUCCESSORS AND ASSIGNS.

This Agreement shall inure to the benefit of and be binding
upon the successors and permitted assigns of the parties hereto. This Agreement
may be assigned by any Purchaser to any permitted transferee of all or part of
the Notes or Conversion Shares. USi may not assign any of its rights under this
Agreement without the written consent of the Purchasers. Except as provided in
this Section 9.3, no Person other than the parties hereto and their successors
and permitted assigns is intended to be a beneficiary of any of the Transaction
Documents.

9.4. AMENDMENT AND WAIVER.

(a) No failure or delay on the part of USi or the
Purchasers in exercising any right, power or remedy hereunder shall operate as a
waiver thereof; nor shall any single or partial exercise of any such right,
power or remedy preclude any other or further exercise thereof or the exercise
of any other right, power or remedy. The remedies provided for herein are
cumulative and are not exclusive of any remedies that may be available to USi or
the Purchasers at law, in equity or otherwise.

(b) Any amendment, supplement or modification of or
to any provision of this Agreement, any waiver of any provision of this
Agreement, and any consent to any departure by any party from the terms of any
provision of this Agreement, shall be effective (i) only if it is made or given
in writing and signed by USi (if applicable) and the Purchasers, and (ii) only
in the specific instance and for the specific purpose for which made or given.
Except where notice is specifically required by this Agreement, no notice to or
demand on any party in any case shall entitle any party hereto to any other or
further notice or demand in similar or other circumstances.

9.5. COUNTERPARTS.

This Agreement may be executed in any number of counterparts
and by the parties hereto in separate counterparts, each of which when so
executed shall be deemed to be an original and all of which taken together shall
constitute one and the same agreement.

9.6. HEADINGS.

The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

9.7. GOVERNING LAW.

This Agreement shall be governed by and construed in
accordance with the laws of the State of Maryland, without regard to the
principles of conflicts of law of such state.

9.8. SEVERABILITY.

If any one or more of the provisions contained herein, or the
application thereof in any circumstance, is held invalid, illegal or
unenforceable in any respect for any reason, the validity, legality and
enforceability of any such provision in every other respect and of the

remaining provisions hereof shall not be in any way impaired, unless the
provisions held invalid, illegal or unenforceable shall substantially impair the
benefits of the remaining provisions hereof.

9.9. RULES OF CONSTRUCTION.

Unless the context otherwise requires, "or" is not exclusive,
and references to sections or subsections refer to sections or subsections of
this Agreement.

9.10. ENTIRE AGREEMENT.

This Agreement, together with the exhibits and schedules
hereto and the other Transaction Documents, is intended by the parties as a
final expression of their agreement and intended to be a complete and exclusive
statement of the agreement and understanding of the parties hereto in respect of
the subject matter contained herein and therein. There are no restrictions,
promises, warranties or undertakings, other than those set forth or referred to
herein or therein. This Agreement, together with the exhibits hereto, and the
other Transaction Documents supersede all prior agreements and understandings
between the parties with respect to such subject matter.

9.11. FURTHER ASSURANCES.

Each of the parties shall execute such documents and perform
such further acts (including, without limitation, obtaining any consents,
exemptions, authorizations, or other actions by, or giving any notices to, or
making any filings with, any Governmental Authority or any other Person) as may
be reasonably required or desirable to carry out or to perform the provisions of
this Agreement.

9.12. PUBLICITY.

Except as may be required by applicable law, none of the
parties hereto shall issue a publicity release or announcement or otherwise make
any public disclosure concerning this Agreement or the transactions contemplated
hereby, without prior approval by the other parties hereto, provided that a
Purchaser may nonetheless communicate with its partners concerning such
transactions and investment in USi and may publish a "tombstone" in the
customary form with respect to its investment. If any announcement is required
by law to be made by any party hereto, prior to making such announcement such
party will deliver a draft of such announcement to the other parties and shall
give the other parties an opportunity to comment thereon.

9.13. JURISDICTION.

Each party to this Agreement hereby irrevocably agrees that
any legal action or proceeding arising out of or relating to this Agreement or
any agreements or transactions contemplated hereby may be brought in the courts
of the State of Maryland or of the United States of America for the District of
Maryland and hereby expressly submits to the personal jurisdiction and venue of
such courts for the purposes thereof and expressly waives any claim of improper
venue and any claim that such courts are an inconvenient forum. Each party
hereby

irrevocably consents to the service of process of any of the aforementioned
courts in any such suit, action or proceeding by the mailing of the copies
thereof by registered or certified mail, postage prepaid, to the address set
forth in Section 10.2, such service to become effective 10 days after such
mailing

9.14. WAIVER OF JURY TRIAL.

EACH PARTY HERETO HEREBY WAIVES, TO THE FULLEST EXTENT PERMITTED BY
APPLICABLE LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN ANY LEGAL PROCEEDING
DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE
TRANSACTIONS CONTEMPLATED HEREBY (WHETHER BASED ON CONTRACT, TORT OR ANY OTHER
THEORY). EACH PARTY HERETO (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR
ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH
OTHER PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING
WAIVER AND (B) ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN
INDUCED TO ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS
AND CERTIFICATIONS IN THIS SECTION.

IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be executed and delivered by their respective officers hereunto
duly authorized as of the date first above written.

USINTERNETWORKING, INC.

By:__________________________________
Name:________________________________
Title:_________________________________

GROTECH PARTNERS V L.P.

By: GROTECH CAPITAL GROUP V, LLC
Its General Partner

By:___________________________________
Name:_________________________________
Title:__________________________________

SOUTHERN VENTURE FUND, II, L.P.

By:_________________________________
Partner

VENROCK ASSOCIATES

By:_________________________________
Partner

VENROCK ASSOCIATES II, L.P.

By:_________________________________
General Partner

SOUTHEASTERN TECHNOLOGY FUND, L.P.

By:____________________________________
Name:
Title:

SIEBEL SYSTEMS, INC.

By:_____________________________________
Name:
Title:

SCHEDULE 1

PURCHASER AMOUNT OF NOTES

Grotech II 1,000,000
Xxxxxx II 750,000
Venrock 430,000
Venrock II 570,000
Southeastern 400,000
Siebel 5,000,000
Total $8,150,000

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