This letter will confirm the agreement of the undersigned to purchase warrants (“Warrants”) of Sand Hill IT Security Acquisition Corp. (“Company”) included in the units (“Units”) being sold in the Company’s initial public offering (“IPO”) upon the...

Exhibit 10.13

                    , 2004

Newbridge Securities Corporation

I-Bankers Securities Incorporated

c/o Newbridge Securities Incorporated

0000 Xxxx Xxxxxxx Xxxxx Xxxx

Fort Lauderdale, FL 33309

Re:     Sand Hill IT Security Acquisition Corp.

Gentlemen:

This letter will confirm the agreement of the undersigned to purchase warrants (“Warrants”) of Sand Hill IT Security Acquisition Corp. (“Company”) included in the units (“Units”) being sold in the Company’s initial public offering (“IPO”) upon the terms and conditions set forth herein. Each Unit is comprised of one share of Common Stock and two Warrants. The shares of Common Stock and Warrants will not be separately tradeable until 90 days after the effective date of the Company’s IPO unless Newbridge Securities Corporation and I-Bankers Securities Incorporated (the “Representatives”) inform the Company of their decision to allow earlier separate trading.

The undersigned agrees that this letter agreement constitutes an irrevocable order for the Representatives to purchase for the undersigned’s account within the twenty trading-day period commencing on the date separate trading of the Warrants up to 1,000,000 Warrants at market prices not to exceed $0.65 per Warrant (“Maximum Warrant Purchase”). The Representatives (or such other broker dealer(s) as the Representatives may assign the order to) agrees to fill such order in such amounts and at such times as it may determine, in its sole discretion. The Representatives further agree that they will not charge the undersigned any fees and/or commissions with respect to such purchase obligation.

The undersigned may notify the Representatives that all or part of his respective Maximum Warrant Purchase will be made by an affiliate of the undersigned (or another person or entity introduced to the Representatives by the undersigned (a “Designee”)) who (or which) has an account with the either of the Representatives and, in such event, the Representatives will make such purchase on behalf of said affiliate or Designee; provided, however, that the undersigned hereby agrees to make payment of the purchase price of such purchase in the event that the affiliate or Designee fails to make such payment.

Very truly yours,

Xxxxxxxx X. Xxxxxxx