xD?Linux, its fast, almost unhackable
Linux, its fast, and more securable than Windows, has less gaping holes than Windows, lends itself to forcing the user to learn troubleshooting skills if they lacked them before, has excellent documentation, posesses the rich Unix history of powerful shell scripting I mean powerful shell scripting, oh and an awesome documentary movie too.
I use both Windows and Linux, Windows for games and a for it's social program(Windows Live messenger) and Linux for any to everything else, at the moment I'm running F14 and I like it.
My Favorites are:
Debian, Fedora, Ubuntu and (for the old dust buster-Dinosaur) Debris Linux(based on Ubuntu 8.04)
Windows is good, but I prefer Linux.