Well dang it! If it ain't one thing, it's another. Okay, I've got Vista installed to it's own new partion. I've got DD10 with OSS installed and the OSS screen appears and boots into XP just fine. Now I'm ready to install my XP into it's own partition. Before starting the XP install from the CD-ROM I booted from the DD10 rescue CD and ran DD from that and hid my existing Vista partition. The plan was that when I installed XP it would just ignore that existing Vista partition entirely. I start the XP installation and get to the point where it asks me where to install XP. I tell it to create a new partion. It does, but it assigns drive letter E:. It's still seing the Vista partion even though I've hidden it and wants to assign that partion as C:, and the CD-ROM drive is D:, so this new partion gets E:. I think maybe it's just a display issue with that intial setup screen so I let the entire XP install continue and finish. Goes through just fine, but sure enough, when I boot into XP, it's STILL drive E:! I try to change it to C: through Disk Manager but it tells me I can't change the drive letter of the System drive (which does make sense actually). The next thing I tried was using DD (from the rescue disk again) to delete the XP partition I had just created, and then create a new but unformatted partion using DD. Then I boot from the XP install CD again hoping maybe with the Vista partion hidden and this partion not hidden (I even made it Active) that XP would take this existing partion as C:. No such luck. Still wants to assign the hidden Vista partion as C: and the XP partion as E:. Next thing, I canceled that XP install right there. Rebooted from the DD rescue disk again and used DD to actually format the new partion as NTFS. Reboot from XP install CD, still wants to make that partion E:. How do I use DD to COMPLETELY hide the existing Vista partion so that the XP install won't see it and will assign C: to it's own system drive? Once I get XP installed in addition to Vista and reactive OSS for the boot, I will configure OSS to hide the opposite OS's partition so each OS will be able to boot itself as C: and won't see the other OS at all. It's been 5 years since I set up dual boot on my old computer so my memory could be a little vague, but I don't seem to remember having this problem with Partition Magic 8 and Boot Magic. It "just worked". (Although that was dual-boot between XP and 98, and I even kept XP on FAT32 instead of NTFS at that time, doing all NTFS this time on the new PC though.) Thanks again!!