I have a sapphire Ati hd 4850 512mb on my old system and it still handles all games when I attach a ssd to it. Any what did you mean by you want it to sell it at 200-300 did you mean $200-$300. I still think that nVidia will be a bad option as it is overpriced compared to an equivalent amd card. Although amd has ruined the Radeon series after buying it from Ati, I'll still go with a Radeon.
What is the resolution of your monitor?