Can't say I ever used such a large partition myself. Perhaps you could use a small, old hard drive as the primary drive, just to have the MBR on it. Vista is smart enough to run o.k if you boot it from a partition other than your primary partition. XP, not so much. You could even install Linux on that smaller drive and use a boot loader to select whatever OS you put on your 3tb partition. Of course that may take some doing ^_^.