I would also recommend Knoppix
(THE LiveCD par excellence) and Korroraa
(has Beryl on it, worked perfectly for me and was my first beryl experience
Those are of course more liveCDs than distros.
They can be installed, but usually people take the more popular distributions, which now almost all have live-CDs.
Well, Kororaa seems to be a Gentoo distribution, so it's probably not recommended if you are new to GNU/Linux.
However, like I said, the live 3D desktop works amazingly well and is fluid even from the live CD.