My vote is for the asus p8z68-v because it has super uefi bios features, in my opinion it looks great, it has won many awards, and asus have a really good reputation, whereas gigabyte are widely disliked (particularly on the overclockers forum)
You might think I'm biased in saying that the Kingston Hyper-X Genesis Blue is better because I chose it, but that is not the case. It is better because it runs at 1600mhz instead of 1333mhz.
Any of the cards are fine, obviously the 6950 2gb is better than the 6870, but I think that the 6870 would be just fine for your needs. Compare the two on anandtech.
Also it is better to go with a non-reference graphics card (one pre fitted with an aftermarket cooler) because they are generally cooler running, quieter and sometimes look better (although do not hesitate to buy a reference card if you see one on offer, they are still great)
The Crucial SSD is the best value for money and most reliable ssd at the moment, ocz drives are well known for early faliure. You will be amazed by how much faster an ssd will make your computer, I have my relatively 'old' vertex 2 in smart response mode (google it, its a clever idea smart response

)
And my computer takes under 15 seconds to get from 'windows starting' to the desktop with msn, skype, and about 10 other programs including coreteemp to open.
Without an ssd, this would take a while. An ssd eliminates 'start up lag'
Also an aftermarket cooler is not necessary unless you want to overclock your cpu. If you do not wish to overclock, you could save a few pennies by going with the i5 2500 or 2400 instead of the 2500k, however having superior overclocking capability for the future if nothing else is a good idea.
It is also worth noting that an aftermarket cooler will almost certainly be quieter and drop temperatures even without an overclock, but it would be non-essential.