|Did you try no password?|
If nothing (as in no keys pressed) works then you may have to try a few other ideas.
One is to boot to safe mode. Boot up and press F8 just after it starts a few times. It should ask for what do you want to do. Select safe mode..Select administrator and no password. If works then clear the user password.
If that fails then consider using http://www.loginrecovery.com/
Or maybe a live linux cd with john the cracker or ophcrack live. There are other ways to get the sam database too. One can use xp disk to repair it.
"The era of big government is over," said Clinton 1996