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Exhibit 10.28

Execution Copy

FOURTH AMENDMENT TO
THE OPERATING AGREEMENT OF
RIGGS CAPITAL PARTNERS, LLC

a Delaware Limited Liability Company

THIS FOURTH AMENDMENT is entered into as of January 1, 2003 (the Third
Amendment), by and between RIGGS NATIONAL CORPORATION (the Managing Member
and a Member), RCP INVESTMENTS, L.P. (a Member) and RCP VENTURE MANAGEMENT
INC. (Investment Advisor) amending the Operating Agreement of RIGGS CAPITAL
PARTNERS, LLC, a Delaware limited liability company (the Company), dated as
of the 30th day of November, 1999 (the Original Agreement), as amended by
that First Amendment dated as of December 1, 2000 to the Original Agreement
(the First Amendment), and amended by that Second Amendment dated as of March
31, 2001 (the Second Amendment), as further amended by that Third Amendment
dated as of November 1, 2002, and as joined by RCP Venture Management Inc. by
Joinder to the Operating Agreement of Riggs Capital Partners II, LLC. The
Original Agreement, the First Amendment, the Second Amendment, the Third
Amendment and Joinder are collectively referred to herein as the Operating
Agreement.

WITNESSETH

WHEREAS, the sole Members of the Company are Riggs National Corporation
and RCP Investments, L.P.;

WHEREAS, the Members and RCP Ventures Management Inc. wish to amend
Section 5.9 of the Original Agreement to state that the compensation to be paid
to the Investment Advisor will be equal to $577,500 per year or .5775% of
$100,000,000;

NOW, THEREFORE, in consideration of the premises and mutual promises
hereinafter set forth, the parties hereto do hereby amend the Original
Agreement as follows:

1.     Section 5.9 of the Original Agreement is hereby amended such that the
Investment Adviser shall hereafter be entitled to a management fee equal to
..5775% of $100,000,000 or Five Hundred Seventy-Seven Thousand Five Hundred
Dollars ($577,500) per anum.

2.     Except as specifically provided herein, the Original Agreement and the
First, Second and Third Amendments shall remain in full force and effect. This
Fourth Amendment may be executed in any number of counterparts, all of which
shall constitute a single instrument. This Fourth Amendment shall be binding
upon and inure to the benefit of the parties hereto and their respective heirs,
successors and assigns.

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Execution Copy

FOURTH AMENDMENT TO
THE OPERATING AGREEMENT OF
RIGGS CAPITAL PARTNERS, LLC

IN WITNESS WHEREOF, the undersigned have set their hands as of the day and
year first above written.

|                                                          |  |                                                                      
|--------------------------------------------------------- |  | ---------------------------------------------------------------------
|Managing Member:                                          |  | Member:                                                              
|                                                         
|RIGGS NATIONAL CORPORATION                                |  | RCP INVESTMENTS, L.P.                                                
|                                                         
|By: /s/ Timothy C. CoughlinTimothy C. Coughlin, President |  | By: /s/ J. Carter Beese, Jr.J. Carter Beese, Jr., its General Partner
|                                                         
|                                                          |  | Investment Advisor:                                                  
|                                                         
|                                                          |  | RCP VENTURE MANAGEMENT INC.                                          
|                                                         
|                                                          |  | By: /s/ J. Carter Beese, Jr.
J. Carter Beese, Jr., Chairman and CEO  

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