I wouldn't get anything higher than a gt440/630, my dad has a system with e5200 and gts 250(upgraded from a 9500gt) and the gpu gets bottlenecked like crazy. I think the ati equivalent would be hd7750.
I tried running a e5200 with gtx 560 ti and it did worse than my mates q9400 with a 9600gt in games like cod black ops crysis 2 dx9.