Well personally I would get the best GPU that your PSU/budget can handle. I would go with 7750 GPU at the least (it doesn't require any extra power from your PSU - not PCI-e power connector needed, just the supported 75w from the motherboard PCI-e slot). The 7850 1 gb would be the next step up, but it all depends on your budget. Most onboard GPU's don't do well with dedicated GPU's (Xfire) from what I've read. Your better off with a decent dedicated GPU than trying to get a cheap/low end GPU to mate up with your onboard GPU.