I'm looking at these 3.
A GT 520
I'm not sure if you guys needed the links but just in case there in too.
One more thing I have the stock 300W PSU.
I have a GT 520
in the machine I'm using now (I3) and runs PCLinuxOS very well, and manygames in Win 7 runs well too
My son has a GeForce 8400
in his computer (Core2 duo) and play many games too, PClinuxOS runs perfectly there.
Whatever your choice it will be fine but if you can choose the newest, it will be supported for a longer time.