Well I can tell you that COH 2 will most likely be more demanding on the CPU rather than the GPU (think Civilization series), and the Witcher 2 isn't terribly demanding at that resolution. A 7850 should suffice for your needs, but if you're looking at the 7950, no love for the 7870? The 7950 is more powerful than all 3 obviously, but it only starts to really shine with higher resolutions and/or multiple monitor setups - this right here would be the deciding factor if you think $80 is more worth it or not. Then there is the overclocking aspect, it's no secret that a 20%+ overclock isn't hard to achieve with these cards either. For the price gap alone these days (average of what seems only $20/$30), the 7870 would be a bit better if you're thinking longer term, or go with the 7950 if you think you might have bigger plans down the road.