Some games are running slow even though requierments are OK?

This definitely sounds like a graphics card issue. Try googling the game title along with graphics card issues to see if anybody else is having those same issues. I have a brand new computer and just got Fallout 3 and was having similar problems with crashing, but they fixed it in some of the updates, now it works no problem and I haven't done anything on my end, but update the game.