Windows 7 and I believe Vista are both imaged based meaning you can install either OS onto a hard drive and plug that hard drive into ANY system and it will boot into Windows, find the drivers that it has and install them.  This is no longer like XP where you could not at any cost, take a hard drive that was installed with XP and transfer it to another system.

It’s simply amazing.  It truly helps in troubleshooting operating system problems.

Corrupt OS?  Plug in new Windows 7 install, see if it boots.  If it does, you know the problem is with the OS and not anything else, for the most part.