I've had the pleasure of taking a special Debian 5.0 distribution (Debian 5.0 i386 XFCE LXDE) for a recent test drive as a virtual machine in Citrix XenServer 5.0.
This single CD distribution comes with two selections for a graphical interface, XFCE and LXDE. XFCE works great and is very similar to the Mac OS X look and feel although your PC is probably equipped with a two or three button mouse.
I didn't have good luck with the LXDE, Lightweight X11 Desktop Environment, although it does look promising. I couldn't use the interface at all. Every time I selected an application, it minimized and the screen started to jitter uncontrollably. I had to shut down the VM and remove it. It's possible that LXDE doesn't like being virtualized. XFCE, on the other hand, works flawlessly and quickly as advertised.
My default installation with XFCE is 1.4GB but includes the full OpenOffice.org suite, graphics programs, support for scanners, and much more.
The system performs well with a single processor and 512MB of RAM for the VM. Once XenTools were installed the graphical interface, in undocked mode, performs at near-native speeds.
If you have a small or old computer or laptop, I highly recommend this distribution but I'd choose XFCE instead of LXDE for the time being. You'll have a computer that's ready to connect to the Internet, create spectacular graphics, and run a full office suite. One of the best parts about this distribution is it's name: Debian. You can't beat Debian for simplicity, ease of updating, ease of upgrading, small footprint, support for the latest hardware, and for being one of the most popular distributions in the world.
If you haven't tried XFCE, you haven't enjoyed the power of a lightweight desktop. Additionally, it's fast and attractive. I don't know what XFCE stands for but for me it's "What Else Do You Need?"
Write back and tell me what you think of this distribution and XFCE. If you have better luck with LXDE, let me know that as well.