EXHIBIT 10.15(a)

                              THE BANK OF NEW YORK
           NEW YORK'S FIRST BANK - FOUNDED 1784 BY ALEXANDER HAMILTON


                                                                April 24, 1998

THINK New Ideas, Inc.
45 West 36th Street
12th  Floor
New York, New York 10018

Attention:  Melvin L. Epstein
            Chief Financial Officer

Gentlemen/Ladies:

      The Bank of New York (the  "Bank") is  pleased  to  confirm  that it holds
available to THINK New Ideas, Inc. (the "Company") a $5,000,000  secured line of
credit for direct borrowings by the Company.

      Extensions  of credit  under this line of credit  shall be  evidenced  by,
shall be payable as provided in, and shall bear  interest at the rate  specified
in, a master  promissory  note of the  Company  in the form  included  with this
letter.

      All  obligations  of the Company to the Bank with  respect to this line of
credit  shall be jointly and  severally  guaranteed  by On Ramp,  Inc. and Scott
Mednick &  Associates,  Inc.  (the  "Guarantors")  pursuant to guarantees in the
forms included with this letter. In addition,  an obligations of the Company and
the  Guarantors to the Bank with respect to this line of credit shall be secured
pursuant to security agreements in the forms included with this letter, executed
by the Company or a Guarantor,  which grant the Bank a first and prior  security
interest in all personal  property of the Company and the Guarantors (other than
any and all  copyrights,  trademarks,  service marks,  patents and other similar
rights and interests of the Company or any of the Guarantors).

      In connection with this line of credit, the Company shall pay to the Bank,
quarterly in arrears on the first day of each January,  April, July and October,
a fee if 1/4% per annum on the  average  daily  unused  portion  of this line of
credit,  which fee shall be  calculated  on the basis of a 360-day  year for the
actual number of days elapsed.

      For so long as this line of credit is held  available  or the  Company has
any obligations  outstanding under this line of credit, there shall be delivered
to the Bank the following,  in each case in form and content satisfactory to the
Bank:


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                             THE BANK OF NEW YORK
                                                                               2



      A.     Within 15 days  after  the  filing  thereof,  a copy of the Forms
10-K  and  10-Q  filed  by  the  Company  with  the  Securities  and  Exchange
Commission;

      B. Within 15 days after the end of each calendar  month, an aging schedule
of the Company's accounts receivable  (including a segregation of the pre-billed
media  accounts  receivable  of the Company) as of the last business day of such
calendar month; and

      C.     Promptly,  such  other  information  as the Bank  may  reasonably
request from time to time.

      As you know lines of credit are  cancellable  at any time by either  party
and, in addition,  (i) the initial extension of credit under this line of credit
is subject to the Bank's receipt of a letter from the Company's certified public
accountants   which  covers  such  matters  as  the  Bank  may  require  and  is
satisfactory  in form and substance to the Bank and (ii) any extension of credit
under this line of credit is subject to the Bank's satisfaction,  at the time of
such  extension  of  credit,  with  the  condition  (financial  and  otherwise),
business, prospects, properties, assets, ownership, management and operations of
each of the Company and each of the  Guarantors,  with the collateral in respect
of this line of credit  and,  if the  amount of such  extension  of credit  will
result in  aggregate  extensions  of credit  in excess of  $1,000,000,  with the
intended use of such extension of credit:  Unless cancelled  earlier as provided
in the first  sentence  of this  paragraph,  this  line of credit  shall be held
available  until March 31, 1999.  Additionally,  all  extensions of credit under
this line of credit shall be reduced to zero for a period of 30 consecutive days
during the period this line of credit is held available.


      THIS LETTER SUPERSEDES IN ITS ENTIRETY THE LETTER DATED APRIL 6, 1998 FROM
THE BANK TO THE COMPANY, WHICH LETTER DATED APRIL 6, 1998 IS OF NO FURTHER FORCE
OR EFFECT.


                                                Very truly yours,

                                                THE BANK OF NEW YORK


                                                By:  /S/ A. Alan Ackbarali
                                                     --------------------------
                                                     A. Alan Ackbarali
                                                     Vice President