Yeah, like Envy said, in 1.6 it's way harder to get headshots. But CS:S is superior to 1.6 is terms of graphics. I also find that the nades in CS:S are alot better, the ones in 1.6 are sluggish to throw compared to the new ones. I'd get CS:S if you can run it at a good framerate, but if you have a crappy machine, then play 1.6.