I don't have experience with those games, but I know they are really demanding. On lower settings though, I think it would run it pretty well.
I got an extra 125MHz stable. The Gigabyte Windforce cards are all made to overclock.
With only touching the multiplier, I got the CPU to 4.0GHz, but when you mess with the voltage and all that, I've heard of people getting it to 4.5GHz. You can probably find a tutorial somewhere for your board.