[offby1 asked me this in a comment to a previous blog post. I replied briefly, then realised I had a lot more to say on the subject.]
I've been a Mandrake user since late 99 or early 2000 or so. I had a brief flirtation with Ubuntu in between, but it didn't work out.
I'm a confirmed KDE fan -- I never liked Gnome philosophically, even before Mono dependencies like F-Spot and Beagle starting becoming standard. I hate the look and feel, I hate the minimalism, and I really, *really*, hated that if I mounted my home directory temporarily on a colleague's Gnome box using the GUI (sftp://sitaram@my.ip.address), Gnome would remember the credentials for a long time afterward, while KDE would obligingly forget about them immediately. [Tested again today; Gnome now has a nice button that says "forget password immediately". Whoo hoo! But does it forget? No! After 2 minutes it still remembered it -- it had kept the VFS session open in the background and just reconnected when the URL was typed in again. I didn't wait around to see when it expires; I just killed the processes that seemed to have the connection open and changed my password just in case! Bloody awful security if you ask me...]
Ok where was I... KDE, right...
But recently, having to install MDV 2009.1 on my dad's old clunker made me realise the charms of one of the alternative desktop+WMs. Specifically, LXDE+openbox -- it's really fast compared to KDE. And when I tried it on my Core 2 Duo + 2GB desktop, I was surprised to find that it makes a difference even on that, so that's what I use now.
Of course, there are many pieces of KDE I need, and like. For example, the hardware volume buttons on a laptop only respond when "kmix" is running, so I run kmix. I still like "konsole" more than "lxterminal". Then there's Okular, dolphin, gwenview (a KDE program whose name starts with a "G" -- go figure!), krusader, all of which I like very much. I just no longer run kwin (the window manager) that's all.
In fact, it actually doesn't matter even if I *install* all of KDE -- hard disk space is not the problem. They just don't get loaded into RAM, that's all.
Downside: I lose all the fancy transparency stuff. That was cute, and even useful sometimes (like typing something into the bottom window while reading off the top window which was at 75% transparency -- very impressive!) but I can live without it.