<PAGE>   1
                                                                   EXHIBIT 10.19
                         NON-NEGOTIABLE PROMISSORY NOTE
                         ------------------------------

                                                                Denver, Colorado
$741,666.00                                                       March 17, 2000


         FOR VALUE RECEIVED, the undersigned, PowerSpring, Inc., a Delaware
corporation (the "Maker"), hereby promises to pay to John A. Harpole (the
"Payee"), at 600 17th Street, Suite 600 South, Denver, Colorado 80202, or at
such other address as the Payee may from time to time designate in writing, in
lawful money of the United States of America, the principal sum of Seven Hundred
Forty-One Thousand, Six Hundred Sixty-Six Dollars and No Cents ($741,666.00),
together with interest on the unpaid principal balance of this Note at the rate
set forth below.

         1. Principal. The unpaid principal balance of this Note and shall be
due and payable in two annual installments, as follows: the first installment
shall be in the amount of $408,333.00 and due and payable on the first
anniversary of the date of the Note; and the second installment shall be in the
amount of $333,333.00 and due and payable on the second anniversary of the date
of this Note.

         2. Interest. The unpaid principal balance of this Note shall bear
interest from the date hereof at a rate per annum of 6.00%. Interest shall be
due and payable in arrears on the same dates as the principal is due as set
forth in Section 1, until the principal sum of this Note and all accrued and
unpaid interest thereon has been paid in full. Such interest shall be computed
on the basis of the actual number of days during which the unpaid principal
balance is outstanding, divided by a 365/366 day year, as applicable, including
the first day but excluding the last day.

         3. Prepayments. The Maker shall have the right, at its option, to
prepay in whole at any time or in part from time to time the unpaid principal
balance of this Note and the interest due thereon accrued to the date of the
prepayment, without penalty or premium.

         4. Application of Payments. All payments shall first be applied to
accrued and unpaid interest and the balance, if any, shall be applied to the
unpaid principal balance of this Note.

         5. Default. If the Maker shall fail to timely make any payment due
hereunder within thirty (30) days after receipt of written notice of default
from the Payee, then at the option of the Payee, exercised by giving written
notice to the Maker, the entire unpaid principal balance of this Note, plus all
accrued and unpaid interest thereon, shall become immediately due and payable.
After the unpaid principal balance of this Note shall have become due and
payable, whether due to maturity, by acceleration or otherwise, then the unpaid
principal balance of this Note, plus all accrued and unpaid interest thereon,
shall bear interest at the rate per annum of the lesser of 12% or the maximum
amount permitted by law.

         6. Waiver of Procedural Defenses. The Maker and all other persons now
or hereafter liable for the payment of all or any part of the principal or
interest due on this Note, including without limitation indorsers, sureties and
guarantors, whether bound by this or separate instrument or agreement, do hereby
expressly waive presentment for payment, demand, notice of non-payment, notice
of dishonor, protest and notice of protest, and any and all other notices and
demands whatsoever, and agree to remain bound hereunder until the principal and
interest on this Note are paid in full, notwithstanding any extensions of time
for payment which may be granted by the Payee, even though the period of
extension may be

<PAGE>   2
indefinite, and notwithstanding any inaction by or failure to assert any legal
right available to the Payee. No conduct of the Payee shall be deemed to be a
waiver or release of such liability, unless the Payee expressly releases such
person in writing.

         7. Severability. If any term or provision of this Note or the
application thereof to any person, property or circumstance shall to any extent
be determined to be invalid or unenforceable, then all other terms and
provisions of this Note, and the application of such invalid or unenforceable
term or provision to persons, properties and circumstances other than those as
to which this Note is invalid or unenforceable, shall not be affected thereby,
and to that end the terms and provisions of this Note shall be severable, and
each term and provision of this Note shall be valid and enforceable to the
fullest extent permitted by law.

         8. No Waiver. No delay or omission by the Payee in exercising any right
or power arising under this Note shall impair any such right or power or be
deemed to be a waiver of any such right or power, nor shall any single or
partial exercise of any right or power preclude other or further exercise
thereof, or the exercise of any other right or power hereunder or otherwise. No
waiver or modification of the terms of this Note shall be valid unless set forth
in writing executed by the Payee, and a waiver on one or more occasions will not
be construed as a consent to or a waiver of any of the Payee's rights or
remedies on any future occasions.

         9. Governing Law. This Note shall be governed by and construed in
accordance with the internal substantive laws of the State of Colorado, without
giving effect to choice or conflicts of law.

         10. Integration; Amendment. The terms and conditions of this Note
constitute the entire agreement among the Maker and the Payee with respect to
the subject matter hereof and supersede any prior representations, agreements or
understandings relating thereto by or between the Maker and the Payee, whether
written or oral. No amendment or modification of this Note or waiver of the
terms or conditions hereof shall be binding upon the Maker or the Payee, unless
approved in writing by such party.

         11. No Assignment. Neither this Note nor the rights or obligations of
the Maker or the Payee hereunder may be assigned, whether by assignment,
transfer, merger, consolidation, sale, operation of law or otherwise, by either
the Maker or the Payee without the prior written consent of the other.

                                   MAKER:

                                   POWERSPRING, INC.


                                   By:/s/ W. Phillip Marcum
                                      ----------------------------------------
                                      W. Phillip Marcum, President

                                        2