I always use ntpasswd when I have a computer with an unknown PW. Read up on how to use it, it'll works like a charm. I have however had one XP machine in probably a hundred which this did not work, I then had to do some more research and ended up finding another app called Wanky in which you load it when doing a windows install when it says press F6 to load 3rd party drivers. I would try the ntpasswd first, dump the SAM accounts, select one, change the password. That will most likely work, if not let me know and I can hook you up with Wanky!