Hi,
I would start by looking at the following thread what I have supplied a link to the most relevant post to this question
Read before posting new threads
I would say you are likely going to be looking at most typically seeing Fedora and Ubuntu come up, but there are others and sites that review them more in depth then people will here, thus why I suggest you check out the link. There are alternatives to Fedora and Ubuntu as well, Mandriva being one I could name... most people generally use Fedora or Ubuntu so that's what I expect to see mainly quoted here.