BTW, colinux is a very promising alternative for those can't get away from XP.
Interesting you should mention it -- one of the developers of Topologilinux (which normally installs in a couple of large files on your NTFS partition, and mounts them as a loop, if I'm saying that right) posted a HOWTO about getting Topo working with coLinux. Haven't played with it yet.

KDE and XP running on the same machine would be pretty interesting.
An easy way to do that is with Cygwin and KDE on Cygwin. I've got both KDE 2 and KDE 3 on my Win2K desktop. They're pretty minimal, but I can ssh into my other Linux boxes and run X apps over the network.

That was 6 months or so ago that I installed them -- since then, Cygwin/X seems to allow you to run X apps in "multi-window mode," alongside Windows apps. Gonna have to upgrade!