This is a pretty easy to follow password recovery procedure for WindowsXP. Essentially you run the Windows XP boot cd in Repair mode and hit SHIFT + F10 during the Installing Devices progress bar. Now you have access to the system.
NUSRMGR.CPL gives you the User Accounts Control Panel.
net user user_name new_password let’s you change a password from the command prompt.
See the linked article for detailed instructions and alternative methods.
I Forgot My Administrator Password!
