i run the ATI RADEON 4670 HD 1 GB PCI-E card and i love it, runs everything with no issue and can have a full 1080p res. i would recomend my card, here are two links for different versions for it.
Micro Center - Radeon HD 4670 1024MB GDDR3 PCIe 2.0 Graphics Card -
same card just amd/ati makes it. $110
Micro Center - Radeon HD 4670 1024MB GDDR3 PCIe 2.0 Graphics Card -
the one i have $100 $80 after rebate