I'm thinking more of the iReboot/EasyBCD situation really. I'm thinking of upgrading one or both of my XP Pro SP3's to Vista Ultimate (now that I have Technet Plus) and wondered if anyone foresees difficulties ahead with an upgrade vs. a clean install? The boot sector is on C: which is XP Pro SP3 #1 which is also where EasyBCD is, I then have D: XP Pro SP3 #2 test OS, then I have M: Vista Ultimate SP1 and N: Windows 7 beta. C: and D: are on disk 0, M: and N: are on disk 1. I'll probably wait until Vista SP2 final is on the download list.