I think this might be a bigger problem than I initially thought. I can't get the old computer to even boot the damn repair CD (it either freezes while loading it or it comes up with a screen saying "Windows failed to start. A recent hardware or software change might be the cause. To fix the problem:"
And then goes on to say I should use the repair disk, which I can't. To make matters worse, it doesn't respond to me tapping F8 on the keyboard at startup, though it does respond to me pressing other keys (F9 for Express recovery, which I need a Gigabyte Mobo CD for apparently, and I don't have it).
Now I'm even more stumped. I think the motherboard must be dying and maybe that triggered this issue with the hard drive?