I was recently given a CD with Ubuntu 9.10 on it, Ubuntu is a version of Linux.
This is a free operating system and can be installed in one of over 60 languages including Gaeilge.
I installed it on an old computer that had windows xp on it that had crashed about 3 years ago
(I just never got around to disposing of it) It turns out it was just a windows problem and not a computer problem.
Anyway I installed the OS as Gaeilge and almost everything is in Gaeilge including the instructions for the games that come with the system.
Other software titles that are included, Firefox, Open Office.
Other options for running this OS include installing as a windows app, run it from a live CD, and dual booting. I tried running it from the CD and decided I like the OS enough that I'd try the old computer since it was just setting in a corner gathering dust.
Anyway if anyone is interested you can download the latest version 10.04 (699 MB) from Ubuntu and burn a CD and give it a try.