<PAGE>

                                                                   EXHIBIT 10.28

                                Form of Convertible Subordinated Promissory Note


NEITHER THIS NOTE NOR ANY SECURITIES WHICH MAY BE ISSUED UPON CONVERSION HEREOF
HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR REGISTERED
OR OTHERWISE QUALIFIED UNDER ANY STATE SECURITIES LAW.  NEITHER THIS NOTE NOR
ANY SUCH SECURITIES MAY BE SOLD OR OFFERED FOR SALE IN THE ABSENCE OF AN
EFFECTIVE REGISTRATION STATEMENT UNDER SAID ACT AND REGISTRATION OR OTHER
QUALIFICATION UNDER ANY APPLICABLE STATE SECURITIES LAWS, OR AN OPINION OF
COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION OR OTHER
QUALIFICATION IS NOT REQUIRED.



                                 DOVEBID, INC.

                    CONVERTIBLE SUBORDINATED PROMISSORY NOTE


$1,425,000                                              March 2, 2000

          DoveBid, Inc., a Delaware corporation (the "Company"), with offices at
1241 East Hillsdale Blvd., Foster City, CA 94404, for value received, promises
to pay to the order of David S. Gronik, Jr. ("Payee") at such address as Payee
may designate, One Million Four Hundred Twenty-Five Thousand Dollars and No
Cents ($1,425,000), plus simple interest thereon calculated from the date hereof
until paid at an annual rate equal to the minimum rate established pursuant to
Section 1274(d) of the Internal Revenue Code of 1986, as amended, as of the date
hereof, compounded annually. Principal and accrued interest will be due and
payable in lawful money of the United States in full on the two year anniversary
of the date of this Note (the "Maturity Date"), unless this Note shall have been
previously converted pursuant to Section 2 below, in which case all outstanding
principal under this Note and all accrued interest thereon shall be satisfied in
full by virtue of such conversion and the issuance and delivery of fully paid
and non-assessable shares of Conversion Stock to the holder of this Note as set
forth in Section 2 below. Payments by the Company shall be applied first to any
and all accrued interest through the payment date and second to the principal
remaining due hereunder.

          The following is a statement of the rights of the holder of this Note
and the conditions to which this Note is subject, and to which the holder
hereof, by the acceptance of this Note, agrees:

          1.  Definitions.  As used in this Note, the following terms, unless
              -----------
the context otherwise requires, have the following meanings:

<PAGE>


                 1.1  "Company" includes any corporation or other entity which
succeeds to or assume the obligations of the Company under this Note.

                 1.2  "Conversion Stock" shall mean shares of Common Stock of
the Company.

                 1.3  "Conversion Price" shall mean the price per share that is
the exact middle of the price range stated in the Company's final amended
registration statement on Form S-1, Form SB-1 or a similar successor form
pertaining to an Initial Public Offering that closes on or before the Maturity
Date. No conversion shall occur and there is therefore no Conversion Price with
respect to an Initial Public Offering that closes after the Maturity Date.

                 1.4  "Noteholder," "holder," or similar terms, when the context
refers to a holder of this Note, shall mean any person who shall at the time be
the registered holder of this Note.

                 1.5  "Initial Public Offering" shall mean the closing of a sale
of Common Stock pursuant to a registration statement on Form S-1, Form SB-1 or
SB-2 (or any similar or successor form) under the Securities Act of 1933, as
amended, for an underwritten initial public offering.

                 1.6  "Subordination Agreement" shall mean the Subordination
Agreement attached hereto as Annex A and incorporated by reference herein.
                             -------
              2. Conversion.
                 ----------

                 2.1  Mandatory Conversion. This Note and all of the outstanding
                      --------------------
principal and accrued and unpaid interest on and under this Note shall be
converted into Conversion Stock at the Conversion Price immediately prior to the
first closing of an Initial Public Offering before the Maturity Date. For
informational purposes, the Company shall provide the Noteholder with written
notice (at the most recent address for the Noteholder provided to the Company by
the Noteholder in writing) (i) within seven days after it files with the
Securities and Exchange Commission any registration statement on Form S-1, Form
SB-1 or Form SB-2 (or any similar or successor form) for an Initial Public
Offering, and (ii) reasonably promptly following the closing of an Initial
Public Offering. Conversion as described in this Section 2.1 shall occur only
upon the closing of an Initial Public Offering, provided that (i) upon the
closing of an Initial Public Offering, the conversion shall be deemed to have
occurred immediately prior to the first closing of such Initial Public Offering,
and (ii) as a condition precedent or condition subsequent to conversion (the
election between which type of condition shall be the Company's sole election in
the Company's sole discretion), the Noteholder must surrender this Note for
conversion at the principal office of the Company. Incident to any conversion,
the Conversion Stock will have those rights and privileges, and be subject to
those restrictions, of the shares of Common Stock as set forth in the Company's
Certificate of Incorporation, and the Noteholder will receive the rights and be
subject to the obligations applicable to the purchasers of Common Stock,
provided that the sale restriction specified in Section 2.5 below shall apply to
the Conversion Stock. This Note shall not be convertible and shall not be
converted into Conversion Stock if there is not an Initial Public Offering on or
before the Maturity Date.

<PAGE>

                 2.2  No Fractional Shares. No fractional shares will be issued
                      --------------------
on conversion of this Note. If on any conversion of this Note a fraction of a
share results, the Company will pay the cash value of that fractional share,
calculated on the basis of the applicable Conversion Price.

                 2.3  Reservation of Stock. Prior to any conversion of this Note
                      --------------------
pursuant to Section 2.1 above, the Company will take such corporate action and
obtain such government consents and approvals as may, in the reasonable opinion
of its counsel, be necessary to authorize the issuance of a sufficient number of
shares of Conversion Stock into which this Note is to convert pursuant to
Section 2.1 above.

                 2.4  Fully Paid Shares; Certificates.  All shares of Conversion
                      -------------------------------
Stock issued upon the conversion of this Note shall be validly issued, fully
paid and non-assessable. The certificates representing the shares of Conversion
Stock issued upon conversion hereof shall be delivered to the holder against
surrender of this Note. The holder, by accepting this Note, undertakes and
agrees to accept such shares of Conversion Stock in full satisfaction of the
outstanding principal and accrued interest thereon in accordance with the terms
of this Note. Anything to the contrary in this Note notwithstanding, the
Company's obligation to issue shares of Conversion Stock to any holder of this
Note is expressly conditioned upon compliance of such issuance with applicable
federal and state securities laws without registration or other qualification
thereunder.

                 2.5 Restriction on Sale. Upon and following any conversion
                     -------------------
pursuant to this Section 2, no holder of any Conversion Stock shall effect any
sale or distribution of any of the Conversion Stock (which shall include any and
all voting securities received by such holder as or in connection with a stock
dividend, stock split or other recapitalization or similar distribution on or in
respect of the Conversion Stock) or any of the Company's other equity
securities, or of any securities convertible into or exchangeable for such
securities, during the period beginning on the closing of the Initial Public
Offering and ending 180 days after such closing. The certificate(s) representing
the shares of Conversion Stock issued upon the conversion of this Note shall be
legended to reflect such restriction on sale.

                 2.6 No Rights or Liabilities as Shareholder. This Note does not
                     ---------------------------------------
by itself entitle the Noteholder to any voting rights or other rights as a
shareholder of the Company. In the absence of conversion of this Note, no
provisions of this Note, and no enumeration herein of the rights or privileges
of the holder shall cause such holder to be a shareholder of the Company for any
purpose by virtue hereof.

                 2.7 No Other Conversion. The conversion described in this
                     -------------------
Section 2 shall constitute the sole methods by which this Note will convert.

              3. Subordination. This Note and the indebtedness evidenced by
                 -------------
this Note are subordinated to all Senior Indebtedness of the Company pursuant to
the terms of a Subordination Agreement in the form attached hereto as Annex A
and incorporated herein by reference.                                 -------

              4. Prepayment.  This Note may be prepaid, in its entirety
                 ----------
(including the principal sum and interest accrued to the date of payment)
without penalty or premium at any time after September 1, 2000; provided that
prepayment cannot take place after the Company has

<PAGE>

filed with the Securities and Exchange Commission a registration statement on
Form S-1, Form SB-1 or Form SB-2 (or any similar or successor form) for an
Initial Public Offering and for so long as any such registration statement
remains pending.

              5. Usury Savings Clause. The Company and the Noteholder intend to
                 --------------------
comply at all times with applicable usury laws. If at any time such laws would
render usurious any amounts due under this Note under applicable law, then it is
the Company's and the Noteholder's express intention that the Company not be
required to pay interest on this Note at a rate in excess of the maximum lawful
rate, that the provisions of this Section 5 shall control over all other
provisions of this Note which may be in apparent conflict hereunder, that such
excess amount shall be immediately credited to the principal balance of this
Note (or, if this Note has been fully paid, refunded by the Noteholder to the
Company), and the provisions hereof shall immediately be reformed and the
amounts thereafter decreased, so as to comply with the then applicable usury
law, but so as to permit the recovery of the fullest amount otherwise due under
this Note.

              6. General Provisions.
                 ------------------

                 6.1  Notices.  All notices and other communications required or
                      -------
permitted hereunder shall be effective upon receipt (or refusal of receipt) and
shall be in writing and delivered by depositing the same in United States mail,
addressed to the party to be notified, postage prepaid and registered or
certified with return receipt requested, by delivering the same in person to
such party or to an officer or agent of such party (or in the case of the Payee
by facsimile), as follows:

               (i)    If mailed or delivered to the Company, to each of the
following, using two separate mailings or deliveries:

                         DoveBid, Inc.
                         1241 East Hillsdale Blvd.
                         Foster City, CA 94404
                         Attn: Cory Ravid, Chief Financial Officer

                         DoveBid, Inc.
                         1241 East Hillsdale Blvd.
                         Foster City, CA 94404
                         Attn: Anthony Capobianco, General Counsel

               (ii)   If mailed, delivered or faxed to the Payee, addressed or
faxed to him at the following address or fax number:

<PAGE>

                         Richard E. Schmitt
                         10111 North Range Line Road
                         Mequon, WI 53092

                         With a copy to:

                         O'Neil, Canon & Hollman, S.C.
                         111 East Wisconsin Avenue, Suite 1400
                         Milwaukee, WI 53202
                         Attn:  James G. DeJong          Fax No. (414) 276-6581

          or to such other address (or in the case of the Payee, the fax number)
as any party hereto shall specify in writing to the other parties hereto
pursuant to this Section 6.1 from time to time. Such notice shall be effective
only upon actual receipt.

                 6.2  Severability; Headings. In case any provision of this Note
                      ----------------------
shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby, unless to do so would deprive the Noteholder or the Company of
a substantial part of its bargain. All headings used herein are used for
convenience only and shall not be used to construe or interpret this Note.

                 6.3  Noteholder Representations and Status. By accepting this
                      -------------------------------------
Note, the Payee and any other Noteholder each acknowledges, represents and
warrants that (i) this Note is being acquired for investment, solely for its own
account and not as a nominee for any other person or entity, and that it will
not offer, sell or otherwise dispose of this Note except as expressly permitted
by this Note and under circumstances which will not result in a violation of the
Securities Act of 1933, as amended (the "Securities Act"), and (ii) he is an
"accredited investor" with the meaning of Rule 501(a) of Regulation D
promulgated under the Securities Act.

                 6.4  Assignment. Neither this Note nor any right or obligation
                      ----------
hereunder may be assigned or delegated by Payee without the prior written
consent of Company. Neither this Note nor any right or obligation hereunder may
be assigned or delegated by Company without the prior written consent of Payee,
except pursuant to a merger in which Company is a party, or pursuant to a sale
or other transfer of substantially all of the assets of Company. Any purported
assignment in violation of this paragraph shall be void.

                 6.5  Amendment; Waiver. Any provision of this Note may be
                      -----------------
amended or modified only by a writing signed by both Company and Payee.
Compliance with any provision of this Note may be waived only by a writing
signed by the party against which enforcement of the change, waiver, discharge
or termination is sought.

                 6.6 Governing Law. This Note shall be construed and enforced in
                     -------------
accordance with, and governed by, the internal laws of the State of California,
excluding that body of law applicable to conflicts of laws.

              [The rest of this page is intentionally left blank.]

<PAGE>

          IN WITNESS WHEREOF, each party has caused this Note to be executed as
of the date first set forth above.

                              DOVEBID, INC.


                              By: /s/ Anthony Capobianco
                                 ---------------------------------------
                              Name:   Anthony Capobianco
                              Title:  Vice President and General Counsel


Acknowledged and Agreed to:

 /s/ David S. Gronik
-----------------------------------------
David S. Gronik, Jr.