Knoppix is a 'live' CD Linux distribution. This basically means you can boot your PC from the CD and hav a working Linux system without having to install anything. I tried an older version a while back, but it didn't like my hardware and seemed to mess up my Windows system. This time I tried version 3.8.1 and it worked fine. I'm intending to install it over the Windows, so it's irrelevant what it does to the hard disk for now.

I just have to work out how to install it to the drive. There's an install script, but that complains about a lack of available partitions and fires up QtParted, a user-friendly partition manager. I'm still working out if I can use that or if I should get geeky with some command-line tools as suggested by Simon. He is running an earlier version at home.