Me? Well it depends, if you play a lot of computer games (from the stores and stuff, not like flash games) then go with XP. But if you don't need pc games then definitely go with Kubuntu, I mean heck I have it on a 3gb hd and that is even enough space with some extra. Barely takes any space at all! That and it's faster, more reliable, no (well, less) virus's, adware, and spyware so no need for any antivirus programs that slow down your computer. Its definitly better performance wise. That and it comes on a livecd which means when you put the cd in and restart your computer then kubuntu will run of your ram until you either take the disc out and restart or, install it on a hd. O and in my opinion light_alistor using 2 hd's to dual boot is way better then using 1. Then you won't have to worrying about deleting important files! Theres plenty of sites that have a lot of free distro's, the only ones that cost money are like Redhat or Suse. Ill look for a couple links.
But if you don't care about video games, or if you want to dual boot between XP and unbutu/kubuntu then yea, definitly go for it. I love it. I think one of the best parts is Linux doesn't take up as much resources, which means if you have a lower end computer then Ubuntu can still run great.
Here is one site:
http://distrowatch.com/
Has a good amount of info and keeps track of hits that a certain distro gets on the right hand side. As you can see, Ubuntu is in 1st ^_^ . You guys can even try Ubuntu Studio which just came out, and is aimed more for graphic and audio enthusiasts. I also recommend PCLinuxOS to beginners too.
http://www.zegeniestudios.net/ldc/
^^ That one is a "test" you can take to see what distro is right for you. Also provides helpful information.
http://en.wikipedia.org/wiki/Comparison ... _and_Linux
wikipedia
http://computer.howstuffworks.com/question246.htm
howstuffworks
rather basic information but always useful to some people. I even found out what kind of liquid they use in Spirit Level's on there!