PROMISSORY NOTE

$1,450,000                                                    New York, New York
                                                               February 28, 2007

            National  Investment  Managers  Inc.,  a  Florida  corporation  (the
"Maker"), for value received, hereby promises to pay to Michael E. Callahan (the
"Holder"),  the  principal  sum of One Million Four  Hundred and Fifty  Thousand
Dollars  ($1,450,000)  (the  "Principal") in such coin or currency of the United
States  of  America  as at the time of  payment  shall be legal  tender  for the
payment of public and private debts, which shall be payable in five installments
as follows: (i) Three Hundred Thousand ($300,000) Dollars payable on November 1,
2007,  (ii) Three Hundred  Thousand  ($300,000)  Dollars payable on May 1, 2008,
(iii) Two Hundred and Fifty Thousand  ($250,000)  Dollars payable on November 1,
2008 and (iv) Three Hundred Thousand  ($300,000)  Dollars payable on May 1, 2009
and (v) Three Hundred Thousand  ($300,000)  Dollars payable on November 1, 2009.
The Maker  further  promises  to pay  interest on the unpaid  principal  balance
hereof at the rate of six percent  (6%) per annum,  interest on the  outstanding
balance to be paid  annually in arrears.  Interest  shall be  calculated  on the
basis of a 360 day year and actual days elapsed.  In no event shall the interest
charged  hereunder  exceed the maximum  permitted under the laws of the State of
New York.

            Notwithstanding  anything  to the  contrary  contained  herein,  the
amount of each of the  installments  described  above is subject  to  adjustment
(downwards  or upwards,  but in no event will the total  payments  of  principal
under this Note exceed  $1,450,000  in the  aggregate,  and in no event will the
installment  payments in the aggregate  exceed  $1,450,000)  in accordance  with
Section 2.3 of the Stock Purchase Agreement,  dated as of the date hereof, among
the Maker, the Holder,  Pentec, Inc. and Pentec Management,  Inc. (the "Purchase
Agreement").  Any such adjustment shall be made to the installment  payment that
corresponds  to such  Measurement  Period  (as  defined  in the  Stock  Purchase
Agreement).   For  example,  any  adjustment  made  in  relation  to  the  first
Measurement Period (as defined in the Purchase Agreement) will be applied to the
first installment payment due under this Note.

            Notwithstanding  anything to the contrary  contained  herein, in the
event the Holder and the Maker submit a dispute  regarding the  determination of
the Adujsted EBITDA (as defined in Section 2.3(a) of the Purchase  Agreement) to
an Independent  Accounting Firm (as defined in the Purchase  Agreement) and such
Independent  Accounting Firm does not issue its report before one of installment
dates set forth  above,  Maker shall not be  required  to make such  installment
payment to Holder until the fifth (5th) business day after such report is issued
by such Independent Accounting Firm.

            This Note can be prepaid in whole or in part at any time without the
consent of the Holder provided that Maker shall pay all accrued  interest on the
principal so prepaid to date of such prepayment.

            The  entire  unpaid  principal  balance  of this  Note and  interest
accrued  with  respect  thereto  shall be  immediately  due and payable upon the
occurrence of any of the following (each, an "Event of Default"):

            a.  Application  for, or consent to, the  appointment of a receiver,
trustee or liquidator for Maker or of its property;

            b. Admission in writing of the Maker's inability to pay its debts as
they mature;

            c. General assignment by the Maker for the benefit of creditors;


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            d. Filing by the Maker of a voluntary  petition in  bankruptcy  or a
petition or an answer seeking reorganization, or an arrangement with creditors;

            e. Entering  against the Maker of a court order approving a petition
filed against it under the federal  bankruptcy  laws, which order shall not have
been vacated or set aside or otherwise terminated within 60 days;

            f. Default in the payment of the  principal  or accrued  interest on
this  Note,  when and as the same  shall  become  due and  payable,  whether  by
acceleration  or otherwise,  which such default has not been cured within thirty
(30) days of the Holder notifying the Maker in writing of such default;

            In the event the Holder's  employment  with the Maker is  terminated
without Cause (as such term is defined in the Employment Agreement),  the entire
unpaid principal  balance of this Note and interest accrued with respect thereto
shall be immediately due and payable on the Termination  Date (as defined in the
Employment Agreement).

            In the event the Maker  experiences  a Change in Control (as defined
below),  the Earned Portion (as such term is defined in the Purchase  Agreement)
of the unpaid  principal  amount under this Note, and all interest  accrued with
respect to the Earned Portion,  shall be immediately due and payable.  A "Change
in Control"  means any of the  following:  (i) any  "Person" or "group" (as such
terms are defined in Sections 13(d) and 14(d) of the Securities  Exchange Act of
1934, as amended (the "Exchange Act")) is or becomes the "beneficial  owner" (as
defined in Rules  13(d)-3  and  13(d)-5  under the  Exchange  Act),  directly or
indirectly,  of 50% or more on a fully  diluted  basis of the  then  outstanding
voting  equity  interests  of the Maker  (other than a "Person" or "group"  that
beneficially owns 50% or more of such outstanding voting equity interests on the
date hereof);  (ii) the Maker sells, leases,  transfers or otherwise disposes of
all  or  substantially  all  of  its  assets;  or  (iii)  the  Maker  merges  or
consolidates  with or into any other  "Person",  or any other "Person" merges or
consolidates  with or into the  Maker,  in each case  unless  the  holders  of a
majority of the  outstanding  voting equity  interests of the Maker  immediately
prior  to such  merger  or  consolidation  continue  to hold a  majority  of the
outstanding voting equity interests of the resulting or surviving entity.

            All rights and  remedies  available  to the Holder  pursuant  to the
provisions of applicable  law and  otherwise are  cumulative,  not exclusive and
enforceable  alternatively,  successively  and/or  concurrently after default by
Maker pursuant to the provisions of this Note.

            This Note may not be changed,  modified or  terminated  orally,  but
only by an agreement in writing, signed by the party to be charged.

            In the event the Maker is found by a court of competent jurisdiction
to have  materially  breached  this Note,  the Holder  shall be  entitled  to be
reimbursed  by the Maker for all costs of  collection  including all court costs
and reasonable  attorney's fees paid or incurred by the Holder in enforcing this
Note.

            This Note shall be governed by and construed in accordance  with the
laws of the  State of New  York  and  shall  be  binding  upon  the  successors,
endorsees  or assigns of the Maker and inure to the benefit of the  Holder,  its
successors,  endorsees  and  assigns.  The  Maker  may not  delegate  any of its
obligations,  or assign any of its  rights,  under this Note  without  the prior
written consent of the Holder.


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            The Maker hereby  irrevocably  consents to the  jurisdiction  of the
courts  located in New York City, in the State of New York and the United States
District  Court for the  Southern  District of New York in  connection  with any
action or  proceeding  arising out of or  relating to this Note.  If any term or
provision  of this Note shall be held  invalid,  illegal or  unenforceable,  the
validity of all other terms and  provisions  hereof  shall in no way be affected
thereby.

                                            NATIONAL INVESTMENT MANAGERS INC.


                                            By: /s/ Leonard Neuhaus
                                            Name:  Leonard Neuhaus
                                            Title: COO


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