Vista Security GPO's Dumped Admin Password

Hi, I'm in the process of attempting to set the appropriate lockdowns on my Vista Ultimate 64 test workstation by use of GPO however, I inadvertently applied a GPO package that upon reboot locked out the built-in admin account by changing its password, and since that was the only account on the machine I can no longer boot into the system. Is there any way to undo or work around this? Help

Use System Restore from WinRE (METHOD I) http://www.vistax64.com/tutorials/76256-system-restore-undo.html

Thanks for the reply. Well, I did method I and unfortunately it didn't work. I only had 1 available restore point and it took me back to the same place I was. At the login screen I put in the Username, and password that it previously was and I get an error telling me "Incorrect Username or Password" additionally, in the area where you would normally see the "Hint" it says "Password Reset..." Are there any other ways that might work? How about a Linux based Password Reset disk?

SUCCESS! After too much time searching I found an instruction how to activate the hidden Vista Administrator. The instructions didn't quite work but with a little creativity I figured out how to do it via the CMD prompt via the OS install disk. Thanks for those that contributed.