So I just built a PC, but due to Windows activation being down, I can't install my Windows 8.1 onto it. I have another hard drive with Windows 7 on it, but I really want to use my new HDD and windows 8.1. If I install my old HDD onto it just to use for the day (they said it'd take 24 hrs) will I just be able to take it out and replace it with my old HDD with no problems? And if I install drivers onto the windows 7 HDD, will they still be there when I install my windows 8.1 HDD?