I've installed Red Hat before. I just didn't like it cause it was so commercialized. Looks like the same thing is happening to Mandriva. I don't want something like that. I am actually quite well imersed in computers, but up until now I only have experience with the various installs of Windows. I have a pretty good working knowledge of OSX now, but now it's time for Linux. I have a very basic knowledge, but nothing too detailed. I want something with a little bit of a challenge to it cause it's the only way I will learn. Hence Gentoo, Suse, or Slackware. They are mainstream enough to be trusted and well-built so I won't get lost, but also less commercialized so it should be advanced enough to learn from.
I messed up when I said different distro's of Gentoo, I meant the different install packages. The two I am looking at are the Universal and Package installations and was wondering specifically what each one was.