I think the best way for Windows users to learn to use Linux (not talking about power users, just the typical clueless Windows user) is to get a Puppy live CD/DVD and play with it. It's the easiest OS to learn, with helpful wizards to walk you through most tasks, very rare to need to use command line.

Even if you decide to stick with Windows, this is a very useful thing to have on hand as a back-up OS. If Windows won't boot, you can use it to fix Windows, or as a substitute. Since the entire OS loads into RAM, you can use it even if your HD has failed completely. It has the option to put its save files on the boot disc, so all your bookmarks
and other data can be available in that situation.

Loaded completely into RAM, it's blazing fast, too - after using it, you may find Windows seems slow and tired. It's fun, too, and safe to experiment with - if you mess it up, just don't save the session and it never happened.