I found this information on Cnet, you could give it a try.
There are two different ways to reset the administrator's password that I have used successfully.
The first is with a commercial package: ERD Commander 2005 that is also available in the Microsoft Diagnostics & Recovery Toolset (a part of the Microsoft Desktop Optimization Pack that is available to companies with software assurance).
The second, and the one that may be easiest for you is the "Offline NT Password & Registry Editor" available free of charge here:
http://home.eunet.no/pnordahl/ntpasswd/
You would have to have a friend download it and burn it to a CD-ROM for you, but after that, it is quite easy to use. In fact, for the purpose you need to put it to, you can simply boot the machine with this CD and accept the defaults all the way through to clear the Administrator's password.
It will simply set the Administrator's password to no password at all. You can then re-boot the machine using the Administrator's login and simply do not enter anything on the Password line. Once you have accessed the machine as Administrator, you can go and change the Administrator's password normally, remembering that the current password at this time would be noting at all.
You may have to change a setting in the machine's BIOS to tell it to boot from the CD-ROM or in some cases, on boot up, you may have the ability to select a boot device by pressing an "F-key". If your machine has this capability, a message should flash up during the machine boot process telling you to Press F(x) on start to select a boot device.
In any event, the download from the site above will create a bootable LINUX disk that can edit the Windows Registry and change passwords (among other things).
One final note: Please be aware that if the Administrator has saved any encrypted files, they will not be available once you have changed the Administrator's password.
Hope this helps...