Okay, noobie alert here!! I currently have a 320 gig hard drive that I want to back up so that I can go from windows xp to windows 7. I currently have only filled up around 82gigs and have had the drive for around 3 years. I don't know if I should buy a prebuilt unit like a "my passbook" or "my book" or build my own with a hard drive and enclosure? Any tips/suggestions? Thanks!