I installed a test Debian on a free disk I had kicking around, to see what the LXDE was like. I have to admit it is small, lightweight and fast. Its pretty too.
It a dead easy install from disk and comes with some pre-installed software, such as Firefox browser, OpenOffice suite, GIMP, Leafpad, and LXTerminal.
They overlooked the most essential app, Emacs, but you can forgive them for that oversight when the rest of the package is so good.
I used a cut down KDE 3.5 desktop for a long time. That worked well for a while, then tried KDE 4.0 a long time after it was released. Waited for the bugs to die, but they wouldn't. Persistent little buggers. KDE 4 kept crashing and hard locking on my box. So I gave up.
I tried Gnome for a while, but felt it was way too bloated. I don't need or use most of the "essentials" that come bundled with most distros. I'm not knocking it, for most people they are great.
For my usage though just give me, Chrome, Emacs, XTerm and I'm happy. Everything else I installed as I need it. Funky fonts included.
LXDE is lightweight. It uses half the RAM of Gnome on Ubuntu. Running it on Debian the thing is lightening fast and immediately responsive. I was getting so bored with Windows 7, which slowed with each passing day.
So if your looking for a cool fast lightweight desktop, have a look at LXDE. You'll like it!