Try Ubuntu. Specifically, the educational version of it, EdUbuntu. Piece of cake to install and it comes with all the tools built-in for FREE. OpenOffice is a magnificent tool (equivalents of excel, word, powerpoint, great database, etc). You can use it as a simple GUI or you can learn the guts of it by learning all the commands for the console. Next step, learn some C or Java. Or better yet, don't do any of that and instead go on hot dates. I think the reward for the latter is more memorable.
But just in case... try this:
http://www.ubuntu.com/