2GB NVIDIA GEFORCE GTX 660 TI Or 2GB ADM RADEON 7950

Have you already purchased the other components? If your sole use for this computer is gaming, maybe you should consider downgrading the CPU to an i5 3570k (more than enough power for gaming), and use the extra $100 to buy a 7970 or 670. Just my thoughts.

I don't know if you'll recieve this, because I don't know how this works. But that sounds like a good idea thanks!

2wenty said is true. If you haven't bought the cpu, get an i5.

HD7970>GTX670 in terms of price and performance. Take your pick

Another important question is what resolution are you playing at? If you are playing at less than 1080p then get a HD 7870 or a GTX 660 and that would be more than enough. If you are playing at 1080p I would recommend the 7950 over the GTX 660 ti because it has double the bandwidth and is more overclockable. With the latest 13.1 drivers it clearly outperforms the GTX 660 ti.

In my opinion you don't need anything more than a 7950 for 1080p. Save yourself a couple of hundred bucks by buying an i5 + 7950.

@9a3iqa

I have to agree with you. Although with the 7870 XT priced at $260 (or possibly lower), I also find it hard to recommend any card more expensive than it for 1080p gaming (although that card is harder to find).

Yes that is another option but as you have said it may not be available  

Nvidia got CUDA, since you mention editing, and some software takes advantage of it. But if I were in your place I would go for the AMD card.