S.T.A.L.K.E.R. (PC)
Do yourself a favour, avoid this game because once you've bought it don't expect the developer or the publisher to care much about you.
I've bought it, and I have reasonably good hardware, but the performance is dire. We're talking jerky movements and low frame rates to the level that they make this game pretty much unplayable.
I've looked in the game forums and I'm not alone, there are people running the latest generation high end graphics cards that are suffering exactly the same problems, so don't expect your latest expensive graphics card to make you exempt from the problem.
On top if you apply the first patch it will make all of your saved games useless. That's right, if you apply the software to fix problems in the game you will end up having to start the entire game again.
So do yourself a favour... avoid this game.