If his psu can handle it i would suggest a 5770.a (very) quick Google, it seems that a single 5770 outperforms a 9600gt sli setup. I have one and you can buy them dirt cheap now,esquire has them at a good price IIRC. That being said, you may find the cost of all these cheap upgrades may end up costing you two thirds of a brand spanking new setup.
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