It's probably best to start off with Mandrake or K/Ubuntu before attempting to install Gentoo. Compiling Gentoo from scratch can teach you more about Linux than using Mandrake will but you have to know how to install it to get the benefits from it. I am currently compiling drivers for my Wireless Network card to work under Gentoo, it's hard work but at the end you feel top of the world.
This site should help some people that want to try Linux decide what Distro is best for them:
http://eedok.voidofmind.com/linux/chooser.html