There is a popular distribution called CentOS that is basically Redhat redistributed under a different license agreement, so you may want to try that. It's used on a lot of servers and stuff.
If you're a noob, just get the latest Ubuntu, it's great.
If you want the 3D stuff, you should try Kubuntu which uses KDE instead of GNOME for your GUI. You'll probably need a decent machine and a 3D video card for this though.
We still use FreeBSD on most of our servers, and I have a home install of Ubuntu just to mess around with, it's great.
CentOS -
http://en.wikipedia.org/wiki/CentOS
Ubuntu -
http://en.wikipedia.org/wiki/Ubuntu_(Linux_distribution)
Kubuntu -
http://en.wikipedia.org/wiki/Kubuntu