UBUNTU
I use Linux on my main computer. Linux is an operating system like Windows, but it doesn't have all those broken parts like Windows does. It's a lot more like Mac OS X, but you have a lot more control over the way everything works. Anyone can install Linux on their computer. All you need is a free* CD. Ubuntu is the easiest 'version' of Linux for a beginner to install. You can download it for free.


*of course nothing is actually free. You have to buy a blank CD and burn the Ubunutu installer onto it.