Download a linux OS from the internet. you know it is free and completely legal don't you?

there are different flavors. the easiest I believe are the ones that have big communities. go with the pack I'd say.

download Ubuntu from www.ubuntu.com they have a Qatari mirror so it is really fast.

install it on a machine. you can dual boot if you have the space on your hard disk drive.

after you install it, go to the ubuntu help sites. one that I can think of is help.ubuntu.com

then read through the manual. its easy.

it somewhat has a steep learning curve. but that is because you are used to windows. after a while, it becomes real easy and you wonder why I have not done this before.

remember to keep reading. if you cant find an answer to something, go to IRC channel #Ubuntu and ask around.

wish you the best.

Burnout.
Beware! :)