I've been looking at KDE4 too, it seems like it has a lot of features, as in maybe too many
Been sold on xfce for sometime, and am using 'screen' a lot lately.
Right now, I am looking seriously at dropping XMonad
on top of xfce as it is *very* powerful, extensible, and could be as super configured as any programmer might want his or her "desktop" to be. You have to jump through several hoops to get it going, but with some basic install skills, it's not too much trouble to put in place. Here's a blurb the XMonad people wrote about xfce:
Why use Xfce with XMonad?
Whilst XMonad is a truly excellent Window Manager, alone it doesn't offer the full convenience of an entire Desktop Environment, such as the provided menus, all-in-one configuration settings, consistent dialogs, etc. Out of the three main DEs available in Unix-like Operating Systems - Gnome, KDE and Xfce - the latter is often touted as the most "nimble" of the lot. In my own opinion, it is simpler to use than KDE but with more configuration options (and a saner environment) than Gnome.
I'd be interested to hear what you think about this, if you decide to take a look.