My experience of gaming in Linux are very negative I must say. Though I only tried with one game, HoN.
Does Linux have DirectX and other nessesary drivers? I dont know. I did not spend eany extra time to find out. But with HoN, I had a very smoth gameplay in Win7 but in Ubuntu on the same computer, it felt like the computer suddenly was 8 years older. Totally unplayable.