I'd suggest against a three core cpu. A lot of programs still can't run with the third core, so you're walking around with a dead limb in a lot of cases. The dual core Athlon or Phenom will be just as affective and cost a little bit less. Athlon II x2 @ 3.2ghz
Also, you don't want to do just one stick of RAM. You're not fulfilling the potential of the dual channel RAM setup. Get 2 * 2 GB sticks or 4 * 2GB sticks for better performance. Also, I had four gb for the longest time with no issue. It works fine. You can upgrade with time, at least this way, you can access all of the dual channel power, rather than just half. G.Skill Ripjaw
Go with this PSU instead. Brand name and after the rebate it costs only 5 dollars more. It's high performance and modular so no problems will come of it unlike non brand names.OCZ PSU
I have an HAF and I hate all the dust issues. Worst buy yet. I love the looks but that's about it. Take my advice if you want to, it's a burden you don't want. Cooler Master makes an incredible line of Mid ATX towers. Their Elite series is awesome!!! Here's one of my favorites. Cooler Master Elite!
Here's a smaller mobo with a bit more kick for the dollar. You can get the one he suggested if you want the longer board. No issue. MSI 880GM
You have a baller system for the price there.
The build I suggested with the mail in rebate and shipping costs comes out to $506 dollars...Go for it bro!