GPU question

I'd let the gtx 550 go and consider either the GTX 560 or the HD6870 as they are about the same. I'd go for the HD6870 as it's the best bang for the buck.
 
6870, I just recently found an interactive chart, I believe on 3D Mark that shows you the best bang for the buck cards according to resolution. the 6870 dominated all but the 1660x900 resolution, but was still like 3rd.
 
The 6870 and 560 are pretty close, look at some benchmarks for games which you play.
 
Nvidia if you are playing heavy tessellation, nvidia designed games or converting heaps of videos, amd for everything else
 
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