Mandriva, used to be Mandrake (www.mandrivalinux.com)
, is my first recommendation for a new linux user. Most say it is a pretty easy install.
I would recommend downloading the distros that the folks here recommend, and loading them one at a time, play with it a few days, and blow it away with the next distro. Each distro has something that appeals to a group of people. There really isn't the "best" distro IMHO, it is just what you like.
I have loaded a good twenty or so different distros over the years. I probably should do a comparison again to see how they all stand.
If you get fairly good with Linux and want to jump in head first, go with Gentoo (www.gentoo.org)
. I find it an excellent all around distro, but it is not for a new user. Start with a stage 2 install.