I like the KDE desktop, and use it with Suse, Debian, Fedora and Kubuntu. They've all come on in leaps and bounds lately, but don't quite do the job that I keep for Windows. Playing Midi files, MP3, and DVDs is still a bit of a pain with most of them, and none of them will drive my colour printer properly. That's Mr Canon's fault for not writing a Linux driver (the Windows driver is almost 60MB!)
I don't think I'll be buying XP's replacement from MS, though. It'll be one of those Linuxes (Linuces? Linuxa?).