If you’d like to play with a unix flavour and don’t mind spending a few dollars you could run out a purchase something small like a Mac Mini. It’s certainly not a screamer in terms of performance but it is pretty cheap, will use your PC keyboard/mouse/monitor and has a BSD Unix core. You can work with a pretty polished GIU or you can go command line to get things done. You get the advantage of running a mainstream OS that has loads of graphic applications, the opportunity to learn a flavour of Unix, and the peace of mind that you are running perhaps the most secure modern OS (there’s really no scary virus or spyware issues.. and you have to apply extra effort to gain root access).
Anyway, those were just my Unix thoughts. I’m not advocating you switch to Macintosh just persenting it as an option where you don’t have to mess with your regular PC box you use day to day to make your money.
Rob