I can't comment on how well it will run on your machine, but most of the glitches have been fixed with updates... although I'm not sure if the Steam version has those same updates, I'd check.
As for the game itself I like Shadow of Chernobyl more than Clear Sky since CS didn't really add that much new stuff, you repeat about 1/2 of the same maps. (the one main improvement was making weapons customizable, for coin) Graphically it's a little more polished, and Vista compatible, but Shadow I prefer as the respawn rates are not as high, and the enemies don't spam you with grenades like in CS. Definitely worth $20 probably one of the most atmospheric games that I've played.