Glad to see more and more people willing to give Linux a try. Here is THE site you need to check out in order to learn more about the different Linux distributions (or distros).
http://distrowatch.com/Also, I posted an online quiz that I found a while ago in another thread. This quiz is IMHO a pretty good starting point to help determine which distro is right for you (at least for the time being). Here's the link to the thread
http://www.dynaverse.net/forum/index.php/topic,163363746.0.htmlI noticed that you were looking at Linux on ebay. Unless you want to get Linspire, Xandros, or one of the other non-free distros, I would recommend downloading Linux for free. Most distros are completely free of charge and offer their CD images to the public for download.
Before jumping head-first into installing Linux, however, I recommend you try out one of the Live CD distros. I recommend starting out with Knoppix, Mepis, or (my personal favorite Live CD distro) Slax. All you need to do is download the disc image, make a CD, and then restart your computer with the CD in the CD-ROM drive, and you're running Linux without installing anything!
Keep in mind that most Linux users try out several distros before settling (if they ever settle) on one distro for their "permanent" desktop. I started out with the free version of Xandros, then moved to Vector Linux, then SUSE Linux, then very briefly to ubuntu, then also very briefly to kubuntu, then back to SUSE Linux, and just yesterday I switched to Slackware (considered to be one of the more "pure" distros). Don't be afraid to jump around and experiment with as many different distros as you like, and above all, have fun.