Excrept from Lifehacker:
Hardcore-user mag Maximum PC shows you how to make the switch to Linux. Specifically, Ubuntu Linux. This exhaustive article covers every step, from downloading and installing the OS to connecting to your network to actually using Linux. The author covers real-world topics like managing photos and music, configuring your e-mail and even setting up a printer. In short, it's as comprehensive a switch-to-Linux guide as you're likely to find anywhere (though here's another one, just for reference). Interestingly, the article itself is open-source: Maximum PC has released it with a Creative Commons attrib-sharealike license, so anyone can download, share and modify it.
You Can Switch to Linux! [Maximum PC]