Originally posted by DJ-CHRIS
It's not stupid that you have reinstall windows
This is not a Windows fault, this is a fact of computing. Your HDD holds drivers and instructions for dealing with all of your hardware. If you rip out the HDD and put it into a totally different box, you've now got a HDD that can't effectively communicate with the hardware because it has improper drivers. Most often it's not a problem, and you can just update things to get them in order again. Sometimes, though, it can totally hose everything.
This is basic knowledge, really.