Yep athlons are kinda no options (limited options for S478 [which is why I didn't bother incluiding them either]).
So that being the case, lookf for those cards up above, because the top of the line GF7800GS is usually way WAY overpriced, and unless you get a gainward it's going to be a crippled card compared to the PCIe versions.
So look at those cards listed, and then put the saving into your next rig.
ALSO IMO anything more than those VPUs I listed will likely be slightly hamstrung by your CPU anyways, so the mid-range makes alot of sense overall too.