I bought a new HP computer that runs Vista to replace an older XP machine. My old system has a Seagate external hard drive that connects via USB. I use that drive for backups, among other things, and it passed Microsoft's Vista compatibility test. In my ideal world, I would shut down my XP machine, disconnect it from everything, and plug the external hard drive into the new Vista machine. Does that ideal world exist, or must I backup all the stuff that's on the external drive and reformat it before I install it on the Vista machine?