They all look pretty good. I would change the HDD to a Samsung Spinpoint F3 1 TB though. It's all around better than that WD. Also, see if you can find CAS Latency 7 sticks of RAM (7-7-7-x).
On the i5 build, I would change the board to an Asus P7P55D-E Pro. The Gigabyte you choose is decent, but if you Crossfire, you lose USB 3/SATA III support. That doesn't happen on the Asus, and they're about the same price.
As far as which one you should go with, I would make another change to the i5 build. I would use the i7-860. The 860 is just as good as the i7, but uses the cheaper chipset.