I downloaded both Xubuntu, which uses Xfce, and Kubuntu, which uses KDE, and burned'em both to bootable CDs.
Xubutnu didn't seem to like my system much at all, but Kubuntu seems to be running faster off the CD than the Gnome version does from the Hard Drive. The interface is also more comfortable and intuitive, thus far. I'm using KDE's own "kustom" browser, Konqueror, to make this post -- it's fast and elegant, and maybe it won't have that distressing FireFox memory leak.
And KDE's mascot is a dragon. Sold!
Just need to move some stuff from the 320-gig to the 80-gig, and it's Clean Install Time!