*sidenote http://digg.com is a great site for tech news. Lots of stupid comments however.*
If you happen to have a spare hard drive sitting around you could do what I do and dual boot. That way when you start up you get the choice which operating system you would like to boot into. You can partition one hard drive and get the same effect as having a second harddrive but you risk the chance of messing up your xp install and I just haven't messed around with partitioning buying a second harddrive was easier

Do you have a cd burner? If you do you can test drive with a live linux cd such as Knoppix or SLAX. This way you can get a feel for the linux terminal and a GUI such as KDE. One of these cd's is a good thing to have laying around too I needed to use it just the other day to fix my windows install after I temporarily broke it. If you decide to go with linux in the long run your going to want a *real* distro (distrobution) I like Debian it is pretty easy and has great documentation. On this box however, I boot into a nice debian based distro called Ubuntu (kbunutu to be exact).

Linux is great and I love the whole open source software scene, but sadly I think dual booting is still the best option for most people's needs. This is because not all hardware, or windows software is fully supported yet. This is changing with development of applications such as Wine and more people writing linux drivers. Try it out at least, you'll learn a ton if you stick with it!