The i7 has hyper-threading which is beneficial for multi-tasking and certain programs that can utilize it (so far no games do).
It also has 2MB more L3 cache, though I'm not up on how much of an impact that has for gaming, guessing not much.
2500k and 2600k Features Comparison
2500k and 2600k Benchmarks
If your primary purpose is gaming, save yourself ~$80 and get the 2500k.
Going down your list:
Samsung Spinpoint F3, performs just as well as the black in real-world applications and is quite a bit cheaper.
i5 2500k, as stated above.
Cases are personal preference, I like the HAF X, but couldn't personally justify spending so much on a case.
At that price would personally go with the MSI Z68A-GD65 or ASRock Z68 Extreme4 both of which have PCIe 3.0, but I keep my computers for years, you may upgrade before this is a relevant technology.
Would not get a Rosewill PSU. On Newegg around the same price you can get a Corsair TX850M or PC P&C Silencer MKII 950W.
Card readers are card readers.
Not really up on mid-range CPU coolers, but believe at the price you could do better with a CM V8/V6, Xigmatek Dark Knight, or Corsair CAFA70.
16GB of RAM is overkill for gaming (4x as much as BF3 recommends), 8GB is more than enough. I'd go with this
, 1600MHz/CAS8 and short heat spreaders.
The model # on the video card links to a 6790, not a 6950. Not sure what the balance is going to be if you save money from the above suggestions, but if you want a kick-butt gaming rig try and swing a 6970 or GTX 570/580.
8-Pin cable extension, not sure why.
24-Pin cable extension, not sure why.
Optical drive is an optical drive.
Don't forget to snag a copy of Windows 7.