I've been playing with the just released, Knoppix 5.0.1 (CD version), over the last few days.
If you haven't tried it yet you should give it a go. A free Linux operating system booting from CD and making no changes to your computer. It really is just a case of popping in the CD.
Unfortunately it only wants to give me 800x600 on my main computer, but the other computer gives me 1024x768. Also I can't make an Internet connection in Knoppix, as I don't think it supports USB DSL modems. Fortunately the (AOL) Internet connection is made on the main computer running XP and so the other computer running Knoppix at 1024x768 is already connected over Ethernet, the network having set itself up automagically in Linux.
Yes if you're a geek you did read that right. An AOL USB DSL connection providing an Internet connection for Linux! :)