The 768mb GTX 460 would be a fine choice for that resolution as I can max out damn near everything with mine using a core i3. But if you plan on stepping up to a larger monitor, adding another monitor, or adding another card for SLI I'd strongly suggest the 1gb GTX 460. And if you do decide to go with an ATI card you can still use your 8800 as a physx card. It is blocked by default by Nvidia, but it will work with a driver hack. Google hybrid physx.