If you want to change the password of any user account you can do it by following this steps:
At First boot you system into Safe Mode. To go to xp safe mode Restart your system
and press the F8 key. (when your pc being restarted) Now you will see a menu. Use the keyboard arrow keys to highlight SafeMode then press Enter & press Enter again on Windows XP now your pc will start in Safe Mode.
You will get Account Log on Screen. click and logon the administrators account. Now have fun with hidden Admin Account.