We take the resolution down to 1920x1200 and see the Multi-GPU adapters doing really aggressive frame rates. But your entry graphics card at 8xAA and this resolution will be the Radeon HD 4850 and you know what, I am still saying GeForce 9800 GTX+ here.

Once we drop image quality towards 4x MSAA, the sky is the limit as not one graphics card released in the past 12 months has a problem. A GeForce 9600 GT for example can do miracles here, as well as the cheapo Radeon HD 4830.

It does seem that last generation graphics cards have an issue. This is mainly memory bound though as 256MB graphics adapters are struggling extremely.