dude its a long one to type. go to google dot com. Search for: how to install linux in [ur machine] . There are millions of articles/forums/tips/blogs you name it. Modify ur search according 2 ur need such as a "dual boot". Make sure u hav access to another computer or you can print em out. The linux you want is free. Download - copy - backup ur files - defragment ...Voila!

I use Ubuntu BTW. Karmic is freakin fast.