x86 platform is the family of processors you find in PCs. Athlons and Pentium family processors are x86.
The advantage of Linux is it's very stable and very secure. The disadvantage is it's a little harder to learn to administrate. Linux can be used to run servers or workstations.
Another advantage of Linux is that it's free to download if you have a fast internet connection (
www.linuxiso.org) or very inexpensive to purchase if you do not (
www.cheapbytes.org, www.easylinuxcds.com, www.osdisc.com, to name a few).
When you obtain Linux, you are getting more than just the operating system (unlike Windows), you get a ton of applications as well.
http://www.linuxgazette.com/node/view/386