<PAGE>
 
                                                                   EXHIBIT 10.11
                                                                   -------------


December 4, 1997

The Registry, Inc.
189 Wells Avenue
Newton, MA 02159

America's Registry, Inc.
189 Wells Avenue
Newton, MA 02159

The Registry, Inc. Network Consulting Practice
157 Portsmouth Avenue
P.O. Box 334
Stratham, NH 03888

Renaissance Solutions, Inc.
Lincoln North
55 Old Bedford Road
Lincoln, MA 01773

The Hunter Group, Inc.
100 East Pratt Street, Suite 1600
Baltimore, MD 21202

Shamrock Computer Resources, Ltd.
800 36th Avenue, Suite 101
Moline, IL 61265

Ladies/Gentlemen:

       Reference is made to the Accounts Receivable Management and Security 
Agreement between us dated February 29, 1996, as supplemented and amended (the 
"Agreement"). Capitalized terms used but not defined herein shall have the 
meanings ascribed to such terms in the Agreement.

       It is hereby agreed that, effective as of December 11, 1997, the 
Agreement shall be amended in the following manner:



<PAGE>
 
      1. Renaissance Solutions, Inc., The Hunter Group, Inc. and Shamrock
Computer Resources, Ltd. are to become borrowers under the Agreement, and the
introductory paragraph is therefore amended to read in its entirety as follows:

          "This Accounts Receivable Management and Security Agreement is made as
      of February 29, 1996 by and among BNY Financial Corporation ("Lender"),
      having offices at 1290 Avenue of the Americas, New York, New York 10104
      and The Registry, Inc. ("TRI") and America's Registry, Inc. ("ARI"), each
      having their principal place of business at 189 Wells Avenue, Newton,
      Massachusetts 02159, The Registry, Inc. Network Consulting Practice
      ("TRNCP"), having its principal place of business at 157 Portsmouth
      Avenue, P.O. Box 334, Stratham, New Hampshire 03888, Renaissance
      Solutions, Inc. ("RSI"), having its principal place of business at Lincoln
      North, 55 Old Bedford Road, Lincoln, Massachusetts 01773, The Hunter
      Group, Inc. ("THGI"), having its principal place of business at 100 East
      Pratt Street, Suite 1600, Baltimore, Maryland 21202 and Shamrock Computer
      Resources, Ltd. ("SCRL"), having its principal place of business at 800
      36th Avenue, Suite 101, Moline, Illinois 61265 (TRI, ARI, TRNCP, RSI, THGI
      and SCRL are hereinafter individually and collectively referred to as the
      "Borrower").

      2. The de"finition of "Change of Ownership" set forth in Section 1(A) is
amended by deleting the abbreviations and words "TRNCP or ARI into each"
appearing in the last line thereof and substituting the abbreviations, words and
punctuation marks "ARI, TRNCP, RSI, THGI or SCRL into any of the" in their place
and stead.

      3. The following sentence is inserted as the end of the first paragraph of
the definition of "Eligible Receivables" set forth in Section 1(A):

      "The Receivables of RSI, THGI and SCRL shall not be deemed to be Eligible 
      Receivables until such time as Lender determines, in its sole discretion,
      that such Receivables are not subject to any security interests or liens
      other than those granted Lender under this Agreement and the Ancillary
      Agreements."

      4. This definitions of "Maximum Loan Amount" and "Maximum Revolving 
Amount" set forth in Section 1(A) are amended to read in their entirety as 
follows:

      ""Maximum Loan Amount" means $50,000,000."
        -------------------

      ""Maximum Revolving Amount" means $50,000,000"
        ------------------------
 
      5. Section (2)(l) is amended by deleting the abbreviations, words and 
punctuation mark "TRNCP and/or ARI" appearing in the first and second sentences 
thereof and substituting the abbreviations, words and punctuations marks "ARI, 
TRNCP, RSI, THGI and/or SCRL" in their place and stead.



<PAGE>
 
       6. Section 8(a)(iii) is amended by inserting the abbreviations and
punctuation marks", RSI, THGI, SCRL" after the abbreviation "ARJ" appearing
therein.

       7. Section 12(m)(i)(f) and 12(m)(ii) are amended by inserting the 
abbreviations and punctuation marks", RSI, THGI, SCRL" after the abbreviation 
"ARI" appearing in each section.

       8. Section 12(m)(vi) is amended by deleting the abbreviations and words 
"ARI or TRNCP can merge into each" and substituting the abbreviations, words and
punctuation marks "ARI, TRNCP, RSI, THGI or SCRL can merge into any of the "in 
their place or stead.

       It is further agreed that we shall waive all currently existing defaults
(the "Existing Defaults") under the Agreement for a period of ninety (90) days
from the date of this letter. If at the end of such ninety (90) day period, you
and we have not agreed to mutually acceptable revisions of the Agreement, this
waiver shall terminate, and we may thereupon exercise all of our rights and
remedies with respect to the Existing Defaults. This waiver is (a) limited to
the specific purposes and time period for which it is given, and no waiver of
any other term, condition, covenant or any other aspect of the Agreement is
intended or implied, and (b) without prejudice to our other rights and remedies
under the Agreement, all of which are hereby expressly reserved.

       Except as hereinabove specifically set forth, the Agreement shall remain 
unmodified and in full force and effect in accordance with its terms.

       If you are in agreement with the foregoing, please so indicate by 
signing and returning to us the enclosed copy of this letter.


                                              Very truly yours,


                                              BNY FINANCIAL CORPORATION
                                               
                                                 
                                              By: /s/ Frank Imperato
                                                 -----------------------
                                                 Title:                  
READ AND AGREED TO:

THE REGISTRY, INC.

By: /s/ Robert E. Foley
   ---------------------
   Title: CFO

AMERICA'S REGISTRY, INC.

By: /s/ Robert E. Foley
   ---------------------
   Title: CFO



<PAGE>
 

THE REGISTRY, INC. NETWORK CONSULTING PRACTICE

By: /s/ Robert E. Foley
   ------------------------
   Title: CFO


RENAISSANCE SOLUTIONS, INC.

By: /s/ Robert E. Foley
   ------------------------
   Title: CFO


THE HUNTER GROUP, INC.

By: /s/ Robert E. Foley
   ------------------------
   Title: CFO
   

SHAMROCK COMPUTER RESOURCES, LTD.

By: /s/ Robert E. Foler
   ------------------------
   Title: CFO