If I get it up and running and learn some linux stuff on it I've always then got the option to stick Win 98 back on it and give it to the charity that I do volunteer work for. They may be setting up 'field workers' in the next year or so, and may then have a use for it. Right now though, I'd like to do some learning.
Chris/dasmi - I know very little of what you speak. I sort of know what linux and BSD are, but being a big wimp I would definitely need a GUI. I do want something that is going to be pretty lightweight, it doesn't need to be pretty, it just needs to function in a way that this Windows user can start to get the hang of. I'm not expecting a great deal, but wireless network access would be nice. Free would be good too.
I have little to no experience of setting up operating systems, so I'm probably going to need something that is fairly self explanatory. I assume the way that this works is that I download a cd image, burn it and sling it into the laptop, after that though the potential for my getting lost is high.