HIS 6850 vs EVGA 560


Aug 8, 2011
I can't decide between these cards.
6850 - http://www.newegg.com/Product/Product.aspx?Item=N82E16814161363
560 - http://www.newegg.com/Product/Product.aspx?Item=N82E16814130660

The 6850 was my original choice, but after researching more about graphics cards, most people seem to prefer Nvidia cards, and the one closest to my budget was the 560. I might overclock either of them slightly, but only until I wouldn't need more cooling or power.
So price and performance wise, would the 560 be better than the 6850? Because it is $15 more.
One thing that worried me is that the 560 has a significantly smaller amount of Stream Processors, does Nvidia count them a different way or something?
The only game I really want to play on max settings is Battlefield 3, other games I'm happy with high, so which one would perform better on BF3?
My other specs are
3.2 GHz Quad Core AMD B55 (Might overclock if I get an aftermarket heatsink)
4 GB RAM (soon to be upgraded to 8GB)
Antec B550 Power Supply
WD 7200 RPM 500 GB HDD (Also going to get 128 GB SSD soon, that's why I want to save my money as much as I can!