Originally Posted by IntellaWorks
If you have a reg backup, you can insert a bootable windows XP cd and select to open the recovery console, which is similar to a DOS prompt.
What is the file name of your reg backup?
If you can put it on a LAN see if you can ping it when it enters windows. If so, you can map a drive to C$ to set admin password, then open regedit on the remote machine and connect to the remote computer.