^If you plan on going with an nvidia gpu, there is no point in getting a crossfire capable motherboard (I really like that motherboard) so I would consider going with a 6850. That way you can crossfire down the road when the gpu starts to show its age.
Dude, if you're building a gaming machine why not build a gaming machine. A quad core is minimum in this day and age and I wouldn't buy a "gaming" processor that didn't have a large amount of L3 cache on it. The only things that really matter for a "gaming" machine are processor and graphics card. Without the "best" you can shoot yourself in the foot. Memory speed is negligible. 1333 is fine and going faster while adding more expense is foolish for the average user. If the 1600 you chose is cheaper go with it. I have no problems with that brand. Used it much more in the past 5 years ( as with what I chose ) that you will in your life time.