One hard drive (SATA) has XP Pro SP3 (I have installation disk) the 2nd hard drive (SATA) has Vista64Bit SP1 ultimate. There is a dual boot, XP first and Vista 2nd. Please, what is the correct way to replace the Vista64Bit Ultimate by the Windows 7 64-Bit Ultimate (regular installation disk)? Or is it a good idea to use Partition Commander 11 sofware to add Windows 7 on one of those hard drives, e.g. XP hard drive (SATA), as a separate system with a separate boot?