Linux

Specifically, Linux Mint.  As far as I could tell from my reading, it is a more user-friendly version of Ubuntu (that statement is probably a gross oversimplification).  Had some issues getting Firefox 4 installed over the included version of 3.6, but I luckily have a geeky little brother who runs a Linux machine, and after a lengthy phone call we got it, Minecraft, and the server program we use to play it up and running.  That was the extent of the issues.  It seems to be a fine operating system.

Oh, and a version of this picture is what I have as my background:

Ahh, the image alterations you can do on your phone these days...