Cant access administration

my computer was a demo at walmart so when my girlfriend purchased walmart had only created a user account on it they didnt create a administrator account so now that i have the unit i cannot do any admin. functions i do not even have a control panel option and everytime i try to access add and remove programs i get an error message stating that i dont have access to this function contact system admin

There are a lot of Windows password revealers and crackers available, but I’ve found that Windows Password Recovery Tool is the most effective.:
it not only supports XP, 2003, 2000, and NT, I have personally tested it with Vista Home Premium and Ultimate. It works perfectly to reset any local user account to a blank password

You can use the ISO to burn a boot CD. Follow these instructions:

1. Download ISO file from http://www.windowspasswordsrecovery.com Windows Password Recovery Tool
2. Burn to a CD using a CD burning tool such as Nero or Roxio or MagicISO
3. Insert CD into drive and reboot.
4. You may have to select an option in the BIOS to get the computer to boot from the CD.

Booting up and clearing a password takes a minute or two works like a charm.