Personally, I would choose mandrake (
www.linux-mandrake.com). It is a very stable disto, and it's very user friendly. They also distribute a live CD version call Mandrake Move. You can download that image and test mandrake out, see if you like it. I have been working with mandrake for about 3 years now, and I live for it. It's amazing, and so secure. If you don't like mandrake though, I would also suggest, like fabyfakid, slackware, semi-userfriendly, very powerfull. Also, SUSE, and Debian, Redhat. these are all good distros, look around though, they're all free!