<PAGE>
 
                                                                    Exhibit 10.6


                                                    American National Bank
                                                    and Trust Company of Chicago

================================================================================
                             DEMAND NOTE UNSECURED
================================================================================
                                        
$3,000,000.00                 Chicago, Illinois                   April 30, 1997
                                                                   Due On Demand

     FOR VALUE RECEIVED, the undersigned (jointly and severally if more than
one) ("Borrower"), promises to pay to the order of American National Bank and
Trust Company of Chicago ("Bank"), at its principal place of business in
Chicago, Illinois or such other place as Bank may designate from time to time
hereafter, the principal sum of THREE MILLION AND NO/100 DOLLARS, or such lesser
principal sum as may then be owed by Borrower to Bank hereunder.

     Borrower's obligations and liabilities to Bank under this Note ("Borrower's
Liabilities") shall be payable ON DEMAND.

     This Note restates and replaces a Demand Note (Unsecured) in the principal
amount of $3,000,000.00, dated April 24, 1996 executed by Borrower in favor of
Bank (the "Prior Note") and is not a repayment or novation of the Prior Note.

     The unpaid principal balance of Borrower's Liabilities due hereunder shall
bear interest from the date of disbursement until paid, computed as follows: at
LIBOR plus 168 basis points, as set forth in the attached London Interbank
Offered Rate Borrowing Agreement, as amended from time to time, by and between
Borrower and Bank; provided, however, that in the event that any of Borrower's
Liabilities are not paid on demand, the unpaid amount of Borrower's Liabilities
shall bear interest after the demand date until paid at a rate equal to the sum
of the rate that would otherwise be in effect plus 3%.

     The rate of interest to be charged by Bank to Borrower shall fluctuate
hereafter from time to time concurrently with, and in an amount equal to, each
increase or decrease in the Base Rate, whichever is applicable.

     Accrued interest shall be payable by Borrower to Bank on the same day of
month and at maturity, commencing with the last day of May, 1997 or as billed by
Bank to Borrower, at Bank's principal place of business, or at such other place
as Bank may designate from time to time hereafter.

     Borrower warrants and represents to Bank that Borrower shall use the
proceeds represented by this Note solely for proper business purposes and
consistently with all applicable laws and statutes.

     Any deposits or other sums at any time credited by or payable or due from
Bank to Borrower, or any monies, cash, cash equivalents, securities,
instruments, documents or other assets of Borrower in the possession or control
of Bank or its bailee for any purpose, may be reduced to cash and applied by
Bank to or setoff by Bank against Borrower's Liabilities.

     Upon demand, all of Borrower's Liabilities shall be immediately due and
payable. All of Bank's rights and remedies under this Note are cumulative and
non-exclusive. The acceptance by Bank of any partial payment made hereunder
after the time when any of Borrower's Liabilities become due and payable will
not establish a custom or waive any rights of Bank to enforce prompt payment
hereof. Bank's failure to require strict performance by Borrower of any
provision of this

                                                                     Page 1 of 3
<PAGE>
 
                                                                    Exhibit 10.6


Note shall not waive, affect or diminish any right of Bank thereafter to demand
strict compliance and performance therewith. Borrower and every endorser waive
presentment, demand and protest and notice of presentment, protest, default,
non-payment, maturity, release, compromise, settlement, extension or renewal of
this Note, and hereby ratify and confirm whatever Bank may do in this regard.
Borrower further waives any and all notice or demand to which Borrower might be
entitled with respect to this Note by virtue of any applicable statute or law
(to the extend permitted by law).

     Borrower agrees to pay, immediately upon demand by Bank, any and all costs,
fees and expenses (including reasonable attorney's fees, costs and expenses)
incurred by Bank (i) in enforcing any of Bank's rights hereunder, and (ii) in
representing Bank in any litigation, contest, suit or dispute, or to commence,
defend or intervene or to take any action with respect to any litigation,
contest, suit or dispute (whether instituted by Bank, Borrower or any other
person) in any way relating to this Note or Borrower's Liabilities, and to the
extent not paid the same shall become part of Borrower's Liabilities.

     This Note shall be deemed to have been submitted by Borrower to Bank and to
have been made at Bank's principal place of business. This Note shall be
governed and controlled by the internal laws of the State of Illinois and not
the law of conflicts.

     Advances under this Note may by made by Bank upon oral or written request
of any person authorized to make such requests on behalf of Borrower
("Authorized Person"). Borrower agrees that Bank may act on requests which Bank
in good faith believes to be made by an Authorized Person, regardless of whether
such requests are in fact made by an Authorized Person. Any such advance shall
be conclusively presumed to have been made by Bank to or for the benefit of
Borrower does hereby irrevocably confirm, ratify and approve all such advance by
Bank and agrees to indemnify Bank against any and all losses and expenses
(including reasonable attorney's fees) and shall hold Bank harmless with respect
thereto.

     TO INDUCE BANK TO ACCEPT THIS NOTE, BORROWER IRREVOCABLY AGREES THAT,
SUBJECT TO BANK'S SOLVE AND ABSOLUTE ELECTION, ALL ACTIONS OR PROCEEDINGS IN ANY
WAY, MANNER OR RESPECT, ARISING OUT OF OR FROM OR RELATED TO THIS NOTE SHALL BE
LITIGATED IN COURTS HAVING SITUS WITHIN THE CITY OF CHICAGO, STATE OF ILLINOIS.
BORROWER HEREBY CONSENTS AND SUBMITS TO THE JURISDICTION OF ANY LOCAL, STATE OR
FEDERAL COURT LOCATED WITHIN SAID CITY AND STATE. BORROWER HEREBY WAIVES ANY
RIGHT IT MAY HAVE TO TRANSFER OR CHANGE THE VENUE OF ANY LITIGATION BROUGHT
AGAINST BORROWER BY BANK IN ACCORDANCE WITH THIS PARAGRAPH.

     BORROWER IRREVOCABLY WAIVES ANY RIGHT TO TRIAL BY JURY IN ANY ACTION, SUIT,
COUNTERCLAIM OR PROCEEDING (I) TO ENFORCE OR DEFEND ANY RIGHTS UNDER OR IN
CONNECTION WITH THIS NOTE OR ANY AMENDMENT, INSTRUMENT, DOCUMENT OR AGREEMENT
DELIVERED OR WHICH MAY IN THE FUTURE BE DELIVERED IN CONNECTION HEREWITH, OR
(II) ARISING FROM ANY DISPUTE OR CONTROVERSY IN CONNECTION WITH OR RELATED TO
THIS NOTE OR

                                                                     Page 2 of 3
<PAGE>
 
                                                                    Exhibit 10.6


ANY SUCH AMENDMENT, INSTRUMENT, DOCUMENT OR AGREEMENT, AND AGREES THAT ANY SUCH
ACTION, SUIT, COUNTERCLAIM OR PROCEEDING SHALL BE TRIED BEFORE A COURT AND NOT
BEFORE A JURY.

                                        "BORROWER"

3040 West Salt Creek Lane               Market Facts, Inc.
-------------------------               a Delaware corporation          
Arlington Heights, Illinois 60005  
---------------------------------                        
Address


                                        BY:  /signed/  Timothy J. Sullivan
                                             -----------------------------------
                                        Timothy J. Sullivan, Senior Vice
                                          President/Treasurer

                                                                     Page 3 of 3
<PAGE>
 
                                                                    Exhibit 10.6


               LONDON INTERBANK OFFERED RATE BORROWING AGREEMENT
               -------------------------------------------------

     THIS LONDON INTERBANK OFFERED RATE ("LIBOR") BORROWING AGREEMENT (this
"Agreement"), dated as of the 30th date of April, 1997 by and between American
National Bank and Trust Company of Chicago ("Bank"), a national banking
association with its principal place of business at 33 North LaSalle Street,
Chicago, Illinois 60690, and Market Facts, Inc. ("Borrower"), a Delaware
corporation with its principal place of business at 3040 West Salt Creek Lane,
Arlington Heights, Illinois 60005, has reference to the following facts and
circumstances:

     A.   Borrower has requested and Bank has agreed to extend an interest rate
          option of 1.68% per annum in excess of the LIBOR; and

     B.   Borrower has executed a Demand Note (Unsecured) dated April 30, 1997,
          in the amount of $3,000,000.00 in favor of Bank, including amendments,
          modifications, extensions, renewals or replacements thereof (the
          "Note") which reflects the LIBOR option.

     NOW THEREFORE, in consideration of any loan, advance, extension of credit
and/or other financial accommodation at any time made by Bank to or for the
benefit of Borrower, and of the promises set forth herein, the parties hereto
agree as follows:

                           1.  DEFINITIONS AND TERMS
                               ---------------------
                                        
     1.1  The following words, terms and/or phrases shall have the meanings set
forth thereafter and such meanings shall be applicable to the singular and
plural form thereof; whenever the context so requires, the use of "it" in
reference to Borrower shall mean Borrower as identified at the beginning of this
Agreement:

          (a) "Amortization Date": the dates specified in the Note when
              principal payments are due.

          (b) "Borrowing": any portion of Borrower's liabilities bearing
              interest at LIBOR.

          (c) "Business Day": any day on which Bank is open for regular
              business.

          (d) "Event of Default": the definition ascribed to this term in the
              Note.

          (e) "Interest Period": the period commencing on the date a LIBOR Loan
              is made and ending , as the Borrower may select, up to 90 days
              thereafter.

          (f) "LIBOR Loans": any principal portion of Borrower's liabilities
              bearing interest at LIBOR.

          (g) "LIBOR Margin": 1.68%

          (h) "Maturity Date": the date specified in the Note upon which
              Borrower's liabilities are due and payable in full.
<PAGE>
 
                                                                    Exhibit 10.6


     1.2  Any terms or phrases not specifically defined in this Agreement shall
have the meanings ascribed to them in the Note.

                          2.  MANNER OF LIBOR ELECTION
                              ------------------------
                                        
     2.1  Borrower may elect to cause all or a portion of the principal
outstanding on the Notes to bear interest at a daily rate equal to the daily
rate equivalent of 1.68% in excess of LIBOR, subject to the following
conditions:

     (a) Not more than five (5) nor less than two (2) Business Days prior to the
         requested date of any LIBOR Borrowing, Borrower shall deliver to Bank
         an irrevocable written or telephone notice setting forth the requested
         date and amount of such Borrowing (which amount shall not be less than
         $500,000.00 and, if in excess of $500,000.00, shall be in integral
         multiples of $50,000.00) and the requested Interest Period of such
         Borrowing;

     (b) The LIBOR used in computing the interest rate applicable to such
         Borrowing shall be the LIBOR as quoted by Bank to Borrower as being in
         effect for the date of such Borrowing plus the LIBOR Margin, computed
         on the basis of a 360-day year and actual days elapsed, and shall be
         fixed for the requested period of such Borrowing:

     (c) Such Borrowing may not be prepaid prior to the expiration of the
         requested Interest Period of such Borrowing and shall be repaid in full
         on the last day of the requested Interest Period of such Borrowing:

     (d) With respect to any Borrowing of LIBOR Loans, Borrower may not select
         an Interest Period that extends beyond the Maturing Date of the Note;
         and

     (e) With respect to any Borrowing of LIBOR Loans under the Note, Borrower
         may not select an Interest Period that extends beyond any Amortization
         Date unless, after giving effect to such requested Borrowing, the
         aggregate unpaid principal amount of such Loans having Maturing Dates
         after such Amortization Date does not exceed the aggregate principal
         amount of the Note scheduled to be outstanding after such Amortization
         Date.

     2.2  In the event Borrower fails to give notice pursuant to Section 2.1(a)
above of the reborrowing of the principal amount of any maturing LIBOR Borrowing
and has not notified the Bank by 10:00 a.m. (Chicago time) on the day such
Borrowing matures that it intends to renew such Borrowing, then Borrower shall
be deemed to have requested a Borrowing of Base or Prime Rate Loans (as defined
in the Note) on such day in the amount of the maturing Borrowing.

                             3.  GENERAL PROVISIONS
                                 ------------------
                                        
     3.1  Funding Indemnity.  In the event Bank shall incur any loss, cost or
expense (including, without limitation, any loss of profit, and any loss, cost
or expense incurred by reason of the liquidation or re-employment of deposits or
other funds acquired by such Bank to fund or
<PAGE>
 
                                                                    Exhibit 10.6


maintain any LIBOR Loan or the relending or reinvesting of such deposits or
amounts paid or prepaid to such Bank) as a result of:

     (a)  any payment or prepayment of a LIBOR Loan on a date other than the
          last day of its Interest Period,

     (b)  any failure by Borrower to borrow a LIBOR Loan on the date specified
          in a notice given pursuant to Section 2.1 hereof,

     (c)  any failure by Borrower to make any payment of principal on any LIBOR
          Loan when due (whether by acceleration or otherwise), or

     (d)  any acceleration of the maturity of a LIBOR Loan as a result of the
          occurrence of any Event of Default,

then, upon the demand of Bank, Borrower shall pay to Bank such amount as will
reimburse Bank for such loss, cost or expense. If Bank makes such a claim for
compensation, it shall provide to Borrower a certificate executed by an officer
of Bank setting forth the amount of such loss, cost of expense in reasonable
detail (including an explanation of the basis for the computation of such loss,
cost or expense) and the amounts shown on such certificate if reasonably
calculated shall be conclusive.

     3.2  Availability of LIBOR Loans.  If Bank determines that maintenance of
its Loans would violate any applicable law, rule, regulation, or directive,
whether or not having the force of law, or if Bank determines that deposits of a
type and maturity appropriate to match fund LIBOR Loans are not available to it
then Bank shall forthwith give notice thereof to Borrower, whereupon, until Bank
notifies Borrower that the circumstances giving rise to such suspension no
longer exist, the obligations of the Bank to make LIBOR Loans shall be
suspended.

     IN WITNESS WHEREOF, this Agreement has been duly executed as of the day and
year specified at the beginning hereof.

                                        Market Facts, Inc.
                                        a Delaware corporation

                                        BY:  /signed/ Timothy J. Sullivan
                                             -----------------------------------
                                        Timothy J. Sullivan, Senior Vice 
                                          President/Treasurer

     Accepted this 30th day of April, 1997 at Bank's principal place of business
in the City of Chicago, State of Illinois.

                                        AMERICAN NATIONAL BANK AND TRUST
                                          COMPANY OF CHICAGO

                                        BY:  /signed/ Peter M. LeSuer
                                             -----------------------------------

                                        ITS:  Vice President
                                             -----------------------------------