For your information, if this issue comes up again...
I don't know what the original problem was that made my video card freak out. When I tried to re-seat the card and reset bios, it fixed the problem with the card.
However, the bios reset lowered my RAM voltage to default, which is 1.8. Being Corsair Dominator's power-hungry self, the RAM was not getting voltage required to make Windows 7 happy enough. After finding a post, days later, that was partially the same as my problem, I gave it a shot and it went straight into Windows 7 installation from the disk.
Apparently, Windows 7 had more requirements than XP, and that allowed me to install XP with no problem.
Thanks for all of your help.