The HD5830 and 9800GTX+ really are not good buys at all. The HD5850 and HD5770 are although the HD5770 is $20 more than you need to spend. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
We need to have more info about your system to make a real recommendation(CPU, PSU, resolution.)
heres my specs:
p6t deluxe v2
western digital 15000 velociraptor
current VGA is his radeon 4870 ice-q turbo but it freezes some times and makes combat arms' charcter/people/zombie lag like hell. and it was not cheap...180$