ahh, I 'm sorry I didn't post this earlier. I jus came across your message again. This will work on XP, never tried it on win 2k. I have to note that it will delete all the user information, including yours, but you will have administrator access.

- make a bootdisk.

- insert bootdisk and turn computer on

- at command prompt type "del C:\Windows\system32\config\SAM"

- reboot and log in using Administrator account without password

basically this just deletes the account information and reset all the usernames. if it doesn't work on win 2k do a search on ur HD for the SAM file. This really should work. Let me know if you're able to do it.