The 560 ti is cheaper than the 6950 that is why I was recommending it because in OP's link or the build he was looking at was the 6950 was $240.00 compaired to the $199.99 560 Ti.
But if you could get the 7850 would be better then both cards and draw less power and what you linked up there is exactly what I was talking about. So I will link you do some bench marks so you can see for your self.
I hope this helps and BTW this is my first build and I made a big boo boo on my GPU's and I have had a lot of time in knowing how to do builds. The 560 ti is the cheaper one. Good luck on your choice. any of the cards are good for the games.
7850 vs 6950
http://www.anandtech.com/bench/Product/510?vs=549
7850 vs 560 Ti
http://www.anandtech.com/bench/Product/547?vs=549
6950 vs 560 Ti
http://www.anandtech.com/bench/Product/293?vs=330