I realize you asked us not to comment on your CPU but I warn you that it will be a serious bottle neck on performance, especially in games. It might not be very bad with only a Radeon 6850 but it's still pretty bad.
You have to realize that FX processors are slower than the previous Phenom II processors and the Phenom IIs are three or four years old. That means that your CPU is outdated and slow as soon as you buy it, putting you at a severe disadvantage and making your machine significantly less future proof than even buying an older Intel Nehalem CPU would, let alone the newer Sandy bridge CPUs or the upcoming Ivy bridge CPUs from Intel.
AMD just isn't a high performance brand anymore, even though some of it's price tags make it seem like it is.
A 990FX motherboard is literally built for crossfire/SLI. You would have been better off getting a cheaper 970 motherboard instead.
I have heard that Gigabyte video cards aren't the best overclocking cards and that Asus, XFX, HIS are better.
For memory, I recommend a 2x4GB 1600MHz 1.5v kit, price should be around $30-45. Recommended brands would be G.Skill, Corsair, and Crucial. I have had and heard the least amount of problems from these brands. Other brands are okay like Patriot, Kingston, and some others but I have heard of many more problems with Patriot and Kingston than with G.Skill, Corsair, and Crucial.
Good thing about memory is that you often get life time warranties, no questions asked so they will be replaced for free if DOA, just incompatible, or if they die a few months/years down the road and will usually even be replaced if they were overclocked.
A few good kits you could consider are:
G.Skill Sniper series
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231416
and Corsair Vengeance series
http://www.newegg.com/Product/Product.aspx?Item=N82E16820233180
Since you went for an AMD CPU you will need to overclock it to get decent performance. To overclock it you will need a good cooler, I'd look for something with a cost of $40-60 for a good one that isn't too expensive.
You can look through the reviews on frostytech.com for a cooler you like and then look at it's price on Newegg.com.