It should do a little better. I have a 4870/512 card. Even with the improved 9.1 drivers it has problems in FarCry2. If it had the extra memory I'm sure it would help.......... 16x10 res.
I read some reviews somewhere that they said to make sure you're running 9.2 Catalyst with the cards to prevent some issues.
Maybe that will help ya. hope so. I know how slowed down cards affect a box.