There are two ways to reset forgotten Administrator password.
Method one – Reset During Repair Reinstall:
Use Win XP installation disk
Run Recovery (not Recovery Console)
Press Shift+F10 during GIU portion of repair / install
Run LUSRMGR.MSC to reset any user password to whatever you want
During my tests, this method always ended up in freeze during a late install stage on “Deleting Temp Files”
Method Two – Use LUNIX bootable CD:
Download free boot CD software from http://pogostick.net/~pnh/ntpasswd/
It might be called Offline Registry Editor, but this utility main purpose is to reset Administrator passwords to blank.
Burn a bootable disk (only 4MB)
Boot from this CD.
Blank Administrator password in registry
In my test utility reset password to all Administrators accounts.