Slightly off topic but important nonetheless:
I'd suggest to get 8 GB RAM, 4 is enough, 8 is fit for the future but 16 is a massive overkill.
Secondly get the i5-2500k, the CPU is just as fast as the 2600k, only thing is it doesn't have hyperthreading, which is fairly useless on multicore CPU's. Especially since most applications don't support or use it.
Thirdly, as a gamer, go for the GTX580. Running two 560 Ti's in SLI will not even get close to the performance of a single GTX580.
The GTX580 will be more expensive, but that's why you get 8GB of RAM and an i5-2500k instead.