Do you plan on overclocking your CPU or GPU at all? Any plans of adding SLI/Xfire in the future?
If you're mostly going to be gaming on this machine I would drop down the 2600k to the 2500k as there is a fairly big price difference and the only performance difference is HyperThreading. You do not need HT for gaming, so I would drop down.
If I were you I would also get a more modern motherboard. Yours will work for this build, but getting a H67, P67, or Z68 will net you a little bit better stability and better features.
That Antec blocked shape thing should not be placed anywhere near a PC. Check out the Corsair enthusiast/gamer/builder series of PSU's, they're very dependable and quite cheap for what they offer.
Bump up to 8GB RAM, it's actually too much, but 4GB isn't enough IMO - and you can't use 6GB without having a motherboard that supports a triple channel kit.
I personally would spring for the 6970 if you want to go AMD, or go with the 570-580 if you don't mind nvidia. It will be a bit more expensive, but again will last much longer and yield better results.
You can drop the aftermarket cooler, if you aren't overclocking past 4.0 you wont need it, the stock one will be fine.
I have never had any luck at all with Antec PSU's. I've tried 4 different models, all of which were either DOA or died within 6 months of installation. For me only Corsair, Thermaltake, and Rosewill will do the job. Perhaps it was all bad luck, but after 4 tries I give up - bad luck or not.