Here's what I'm working with: WinFast NF4UK8AA motherboard AMD Athlon 64 3000+ 1.80 GHz 1.00 GB RAM NVIDIA GeForce 6600 GT Two Seagate SATA hard drives - 250 gig at Location 0 (Channel 1, Target 0, Lun 0); 80 gig at Location 0 (Channel 0, Target 0, Lun 0) Here's the situation: I recently bought an OEM Windows XP Media Center Edition from newegg to replace my less-than-legal Windows XP Professional. Before I installed the new purchase, I cloned my C drive (250 gig) to the D drive (80 gig) using XXclone. Then I formatted the 250 gig drive and did a clean install of Media Center Edition on it. Now at some point during the process, the drive letters switched and the C drive became the 80 gig and the D drive became the 250 gig. Whenever I booted up, I was given the choice to either boot up using the Media Center edition (250 gig) or the cloned XP Pro (80 gig). Both worked fine. After successfully installing and updating Media Center Edition on the 250 gig drive and moving over all the old files I needed from the cloned drive, I formatted the 80 gig drive and installed the Windows Vista RC1 that came with my purchase on it. Now whenever I boot up, it automatically boots Vista off the 80 gig. I have changed the hard disk boot priority from the 80 gig first to the 250 gig, but I always receive the error "Disk boot failure, please insert system disk and press enter." I also ran checkdisk on the 250 gig drive and no problems were found. I suspect that I may have mixed up my hard drive cables, making the 80 gig the primary one, when I want my C drive to be the 250 gig. But I could boot from it before, so I don't know. Any suggestions?