Any PCI-e card will do, but like I stated before, you can get the 8800gt. You might be limited by the CPU, but at least you won't be limited by the GPU. It's up to you. You could go and get a 3850 for ~$170, but I think since your already have the $ for a 8800gt, why not just get it. I don't know how much of a performance difference you'll get with the 3850 to 8800gt, but should be enough to consider. Just make sure you get a good PSU to run the 8800gt.