well, i dunno how its nowadays, but in past radeon was lame, and it has one weird thing - shitty shader support... it resulted in ugly non-filtrated shadows, and crazy bump ( u needed to set it to very hight quality in drivers, to get ok-looking bump maps, but that will be huge strike at performance) ...
dunno maybe they fixed it on rv7xx.
but my rv5xx shadows and bumps make me shit-brick for 2 years...
only thing that run good on radeons is Marks ... but, wtf, who play marks ? t_t
so for gaming i would recommend Nvidia ... for other things - Radeon ...
I was really upset when have bought radeon x1950pro instead of nvidia 8600gts...
so think twice and look at screenshots and fps, not just fps...