Processor: Overkill for gamers. If you do not render or encode or use media (heavily) it's plain ridiculous to take this. Take the 2500, as a gamer you will never notice the difference. The 2600 is the top cpu on the market, I sincerely doubt you'll ever use even half of its performance.
Motherboard: Very good choice, the Z68 series is newer, but has same features as the P67. The only thing it has 'more' are features of the H series (and a tad more) which are basically again aimed at encoding and rendering.
Memory: Take 8gb unless you planning on running a gazillion virtual machines? If not, 8gb is the most anyone needs at the moment.
Graphics: Good choice. If you want to unlock them and overclock them you can get them to perform higher than stock 6970's.
Case: Seems a bit small to me, if you can fit in your 6950's and it has decent cooling then go for it
PSU: Never used a Silverstone PSU. I'd choose Corsair but shouldn't matter that much (if the PSU is 80plus etc. certified).
Again. That processor has no benefit if you're only interested in gaming. It's 100$ you could spend somewhere else.
The Bluray writer is your own choice, though external disks are still cheaper. Although, depending on where you live, if a BD disc price is low (sometimes even only 1-2$) it's still a decent solution.