Intel D915GAV mobo I dont think i would be able to upgrade my cpu any further. I am just looking for a card that will run better than my current ati x550. I was thinking about getting an ati x800 XL , but i still dont know if my computer can run it.
I wouldn't go overboard on a video card for that system since at some point you will be limited by the CPU (and severely by the RAM). You can get a BFG 8600GT for $50 from NewEgg or even better a Radeon 4670 for $80. But memory is pretty cheap now, so if you are investing in that computer, I would look at jumping up to 1 or 2GB.