Ditch the nVidia cards and pick up some of the new ATI DirectX 11 cards (5xxx series). These will perform better, and will be more future proof.
Unless that HDD is a 7200.12, scrap it for a Samsung Spinpoint F3 1 TB. This is probably the best value out right now. The 7200.12 is similiar, but the previous version (7200.11) was plauged with problems.
I've never head of that PSU maker. You should only buy PSUs from the major players, or you could doom your whole build. I highly recommend Corsair, OCZ or Antec.
Gaming the i7 isn't worth the money. Better off using a i5 system and buying better ie GPU, ie 5850 or 5870 and a SSD.
i5 vs i7 have nearly identical fps in most benchmarks with no significant difference. However i5 min fps is significantly higher. Also, no game on the market makes us of 8 threads, heck, none i know of even makes use of 4 threads.
Anandtech or tom's did a test earlier this year comparing gaming performance in 1,2,3 and 4 cores and found that biggest performance increase was in 1 to 2 and 2 to 3 cores. 3 to 4 cores made only a tiny, and real world unnoticeable, difference.
I wouldn't bother with a SSD. The cost you pay would get you very little.
The i7 would help with the encoding, but the i5 would be better for strict gaming. So I gues the OP needs to decide if they do enough encoding for the extra $100+ to make sense. If it's only occasional encoding, definitely go with the i5.