I mainly just need to make sure everything is compatable.
my hard drive is out of stock tho and my friend who helped pick everything is gone so it would be very nice if someone could hold my hand and help pick a better or equal to HDD.
If you want a nice case and have enough space for it this is about the best cases get as far as cooling and noise goes but unfortunately its out of stock you could try the 03 or non evolution which are similar but smaller and bigger respectively but they are all probably overkill if you are loking exclusively for proformance
The case is largely up to you because the difference in cooling is very small and could be compensated for in other areas. The main reasons to get a nicer case is that it is easier to work with and looks nicer. If this is your first build you may want to consider a full tower such a the raven 02-e. I have that case and love it and it was very easy to work with. Heres an article to refer to if you get a cheaper case http://www.tomshardware.com/reviews/nzxt-gamma-rosewill...
As for processor an i5 2500k would preform significantly better for a similar price but it wouldn't have any performance boost in BF3 just more of something that will help you in the future as most games are gpu bottle-necked nowadays anyway. Im just thinking that as time passes you will be able to upgrade to running 2 6970s with the only necessary upgrade possibly being the psu but then your cpu might be holding you back at that point in time and amd is not looking very promising with their cpus. Just an idea. As for the crossfire problems I can't find any but I may be wrong . Other than that everything looks good but if its not a big difference in price you might want to up the psu to 850 w so you can add another 6970 in the future. Hope this helps.
Futuremark results suggest that your CPU will bottleneck your 6970.
Either get on the intel train or drop to 6950 (oddly enough gtx 570 has a nice stepping)
Ask around for someone with better knowledge on this.