If you are running Windows 7 or a variant of Linux then you should be able to remove the hard-drive and place it into another machine and it will re-detect the drivers on the new system and let you use it without much fuss. Granted Windows may ask for a few new drivers that aren't already on the system.
Probably not without reinstalling the OS. With Windows, for example, even if there where no hardware driver issues, WGA would shut you down.
I don't think it should matter. It should just work.
You risk frying your board, so do the research. Have you tried adding it on as a slave first to check if it may need any formatting?
Okay, if it doesn't work as a slave it won't swap either. Make sure the original still starts up alone. When you tried swapping it, what response did you get?
computer geeks this is something i dont deal with better call chad
It doesn't make any difference.