hardrive swap

could i take the harddrive from my current machine and put it into a compelty different one with no problems?

i expect windows would throw a fit and ask for the license key, and i'd need to install driers for different sound/video cards, and CD drives, but other than that would it work completly like normal?

and in regards to windowns license keys, would repeating this  till the end of time be illegal, or is this allowed?

Woah woah woah since when does windows ask for you to reenter a cd key if you're just moving a harddrive to another box.