A P3-450 should still be a useful system, and I make plenty of good use of it. But I've done so by remaining fairly agnostic in the 'Desktop wars' that go on in the land of software bloat: I don't run a KDE or Gnome-based desktop, I have a years-old well tweaked
There are limitations in using this for a Window Manager, but none that really impede my use. I run Sylpheed for email, use the Xfe file browser, and (of course) Mozilla SeaMonkey for my main portal to the 'Web.' I don't really do 'K' anything and consider GTK to be a bunch of useful widgets, not something to base my world around.
There are a bunch of Window Managers in the NetBSD packages collection that I haven't tried. I thought it would be an interesting discussion to discuss the alternative classic 'X Window System' window managers (as opposed to the all-and-mighty 'Big Two' Desktop Environments.) Is there any cool stuff being done with Motif, now that it's free? What are the best window managers out there in 2007?