just started using linux in anger recently, got gentoo installed on my laptop, everything worked a treat, just had to spend a bit of time on the dumbass ATI drivers.
was playing city of heroes yesterday at faster framerates than windows would run it!! this is through cedega, which admittedly i dont like to pay for but...at £3 a month it is not so bad...considering what i would have to pay for a firewall, anti virus, anti spyware and all the little 'extras' that you NEED to make windows a safe place to live.
as far as which distro, id recommend Gentoo, not billed as beginner as such, but you learn a whole lot about linux, configuration, etc. plus the documentation, wiki and forums are the best I've found.
just my $0.02