Now that Fedora 12 is about 17 days away, I'll be burning it then and hoping for the best. If that fails, I'll have to make sure there's a bug report for it. No time to try for a beta release now on my rather poor DSL.
Thanks for the replies thus far. I'm not sure yet whether Fedora is not working on this system because of the X800 GPU or the fact that the card is a flashed PC model, either. Do ye think that would make a difference? It can be quirky in Mac OS X, having minor graphics glitches that will disappear with the installation of ATI's own driver release meant for Tiger.