OK, at this point I think the universe just plain doesn't want me installing this. I try to install Kubuntu 10.04, and it fails to mount the filesystem. Searching the net it seems like it's a fairly common problem, and I couldn't find an authoritative solution, lots of people found different answers that didn't always work. Seems to be an issue with the disc/drive, so maybe if I can scrounge up a flash drive and install from that it might help. Of course, if anyone here has any ideas I'd love to hear them too; I'm basically going to try everything I can find, one by one until I hit on one that works.
EDIT: Yeah, I saw that thread, I actually had the same problem on my FreeBSD desktop and used that exact fix. In a pre-install environment, however, I can't modify it on the target machine as it doesn't have it's own filesystem at this point. The only way I can think of to implement it is to extract the ISO, modify it's xorg.conf, and rebuild it with the modified file. I may have to do this if I can't get Kubuntu to play nice though.