Contract

Exhibit 10.61

SUPPLEMENT NO. 2 (this “Supplement”) dated as of March 17, 2006, to the Guarantee and Collateral Agreement dated as of April 22, 2005 (the “Guarantee and Collateral Agreement”), among DELTEK SYSTEMS, INC., a Virginia corporation (the “Borrower”), each subsidiary of the Borrower from time to time party thereto (each such subsidiary individually a “Guarantor” and collectively, the “Guarantors”; the Guarantors and the Borrower are referred to collectively herein as the “Grantors”) and CREDIT SUISSE (formerly known as Credit Suisse First Boston and referred to herein together with its affiliates as “Credit Suisse”), as collateral agent (in such capacity, the “Collateral Agent”) for the Secured Parties (as defined therein).

A. Reference is made to the Credit Agreement dated as of April 22, 2005 (as amended, supplemented or otherwise modified from time to time, the “Credit Agreement”), among the Borrower, the lenders from time to time party thereto (the “Lenders”), and Credit Suisse, as administrative agent for the Lenders and as Collateral Agent.

B. Capitalized terms used herein and not otherwise defined herein shall have the meanings assigned to such terms in the Credit Agreement or the Guarantee and Collateral Agreement referred to therein, as applicable.

C. The Grantors have entered into the Guarantee and Collateral Agreement in order to induce the Lenders to make Loans and the Issuing Banks to issue Letters of Credit. Section 7.16 of the Guarantee and Collateral Agreement provides that additional Domestic Subsidiaries of the Borrower may become Guarantors and Grantors under the Guarantee and Collateral Agreement by execution and delivery of an instrument in the form of this Supplement. The undersigned Domestic Subsidiary (the “New Subsidiary”) is executing this Supplement in accordance with the requirements of the Credit Agreement to become a Guarantor and a Grantor under the Guarantee and Collateral Agreement in order to induce the Lenders to make additional Loans and the Issuing Banks to issue additional Letters of Credit and as consideration for Loans previously made and Letters of Credit previously issued.

Accordingly, the Collateral Agent and the New Subsidiary agree as follows:

SECTION 1. In accordance with Section 7.16 of the Guarantee and Collateral Agreement, the New Subsidiary by its signature below becomes a Grantor and Guarantor under the Guarantee and Collateral Agreement with the same force and effect as if originally named therein as a Grantor and Guarantor and the New Subsidiary hereby (a) agrees to all the terms and provisions of the Guarantee and Collateral Agreement applicable to it as a Grantor and Guarantor thereunder and (b) represents and warrants that the representations and warranties made by it as a Grantor and Guarantor thereunder (giving effect to any supplements to schedules thereto delivered in connection herewith) are true and correct in all material respects on and as of the date hereof. In furtherance of

the foregoing, the New Subsidiary, as security for the payment and performance in full of the Obligations (as defined in the Guarantee and Collateral Agreement), does hereby create and grant to the Collateral Agent, its successors and assigns, for the ratable benefit of the Secured Parties, their successors and assigns, a security interest in and lien on all of the New Subsidiary’s right, title and interest in and to the Collateral (as defined in the Guarantee and Collateral Agreement) of the New Subsidiary. Each reference to a “Grantor” or a “Guarantor” in the Guarantee and Collateral Agreement shall be deemed to include the New Subsidiary. The Guarantee and Collateral Agreement is hereby incorporated herein by reference.

SECTION 2. The New Subsidiary represents and warrants to the Collateral Agent, for the benefit of the Secured Parties, that this Supplement has been duly authorized, executed and delivered by it and constitutes its legal, valid and binding obligation, enforceable against it in accordance with its terms.

SECTION 3. This Supplement may be executed in counterparts (and by different parties hereto on different counterparts), each of which shall constitute an original, but all of which when taken together shall constitute a single contract. This Supplement shall become effective when the Collateral Agent shall have received counterparts of this Supplement that, when taken together, bear the signatures of the New Subsidiary and the Collateral Agent. Delivery of an executed signature page to this Supplement by facsimile transmission shall be as effective as delivery of a manually signed counterpart of this Supplement.

SECTION 4. The New Subsidiary hereby represents and warrants that (a) set forth on Schedule I attached hereto is a true and correct schedule of (i) any and all Pledged Stock and Pledged Debt Securities now owned by the New Subsidiary and (ii) any and all Patents and registered or pending Trademarks and Copyrights now owned by the New Subsidiary and (b) set forth under its signature hereto, is the true and correct legal name of the New Subsidiary and its jurisdiction of organization.

SECTION 5. Except as expressly supplemented hereby, the Guarantee and Collateral Agreement shall remain in full force and effect.

SECTION 6. THIS SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

SECTION 7. In case any one or more of the provisions contained in this Supplement should be held invalid, illegal or unenforceable in any respect, the validity, legality and enforceability of the remaining provisions contained herein and in the Guarantee and Collateral Agreement shall not in any way be affected or impaired thereby (it being understood that the invalidity of a particular provision in a particular jurisdiction shall not in and of itself affect the validity of such provision in any other jurisdiction). The parties hereto shall endeavor in good-faith negotiations to replace the invalid, illegal or unenforceable provisions with valid provisions the economic effect of which comes as close as possible to that of the invalid, illegal or unenforceable provisions.

SECTION 8. All communications and notices hereunder shall (except as otherwise expressly permitted by the Guarantee and Collateral Agreement) be in writing and given

as provided in Section 9.01 of the Credit Agreement. All communications and notices hereunder to the New Subsidiary shall be given to it in care of the Borrower as provided in Section 9.01 of the Credit Agreement.

SECTION 9. The New Subsidiary agrees to reimburse the Collateral Agent for its reasonable out-of-pocket expenses in connection with this Supplement, including the fees, other charges and disbursements of counsel for the Collateral Agent.

IN WITNESS WHEREOF, the New Subsidiary and the Collateral Agent have duly executed this Supplement to the Guarantee and Collateral Agreement as of the day and year first above written.

WST CORPORATION d/b/a WELCOM
by		/s/ Xxxxxxx X. Xxxxx
		Name: Xxxxxxx X. Xxxxx
		Title: Secretary
		Address: 00000 X. Xxxxxxx Xxxxxxx, Xxxxx 000, Xxxxxxx, XX 00000 Legal Name: WST Corporation Jurisdiction of Formation: Texas
CREDIT SUISSE, CAYMAN ISLANDS BRANCH (formerly known as Credit Suisse First Boston, acting through its Cayman Islands Branch), as Collateral Agent,
by		/s/ Xxxxx Xxxxx
		Name: Xxxxx Xxxxx
		Title: Managing Director
by		/s/ Xxxxxx X. Xxxxxxx
		Name: Xxxxxx X. Xxxxxxx
		Title: Associate