A 550W should be able to run this fine, but I agree with looking at something beefier for later GPU upgrades.
I would also consider the Corsair TX750
and OCZ ZT 750
, but any option linked is quality.
I agree with going for 8GB of RAM, but would stick to 1.5v over 1.65v
and G.Skill Ripjaws X
are both good options.
The HAF 922 is a good case, I just don't agree with the pricing.
For ~$100 you should be able to get USB 3.0 on the front panel and a painted interior.
The Rosewill Blackhawk Nukem linked is nice, as well as the Corsair 400R
and Cougar Evolution
But its really personal preference, so go with what you want to look at.
I would also consider the Corsair CAFA70
$10 more up-front, $5 less after rebate, comes with 2 fans stock, slightly better performance.
I was going to suggest the MSI Z68A-GD55 (G3) motherboard, but considering budget you're probably better with the P8P67 Pro.
They are the same price, but the Asus has a ton more combo deals available.
Don't forget a copy of Windows, and to check for combo deals and rebate codes.