4745454b :
I said stock. I never said what an OC'd 7500 could do. Once your at 1920x1080 most of the burden is on the GPU no matter what. If your still on 1680x1050 then the CPU will matter more.
You asked Stock ? as the OP never mentioned if there was an OC present or not same as the OP never mentioned what resolution was being used.
Given the card being used now we can guess at a lower resolution and we can guess that as no OC was mentioned then there isn't one.
However the op asked "How good of a video card could this processor handle?" I'm just answering the question is all.
Given the facts at my disposal i think a 5770 is well on the low side and probably a 6850 would be a good balance but as the question was "How good of a video card could this processor handle?" and not what would be the best balanced card .......
Answer as already posted, given a decent Over clock i see no reason for a E7500 to be an issue to a 6950.
The main issue will be games that like more than two cores, there you will see the real difference.
Mactronix