My brother was really big into counterstrike but for some reason I could never get it to run on my computer. I have no clue why. I ran half-life just fine on my system. I was quite pissed about it all in all.
I highly reccomend Day of Defeat half-life mod. Its a squad level WWII combat mod. There seems to be fewer 12 year olds ruining the gameplay than with other online games.