I think one of the Corsair 650W psu's was that price after rebates or savings or something. With that case I'd get the Xigmatek S1283. Also, unless you don't plan on ever upgrading, I'd switch to the Gigabyte X48-DS4. X48 is better for crossfire so you can get a second 4850. Crossfire 4850's are awesome. Other than that, great build. I think there's Mushkin ram with lower timings and cheaper after rebates, check NewEgg. Other than that, great build.
Nice job. Check out the 650W Corsair PSU. It's the same price as the one you're getting, very efficient, and single rail. Also you can get a 22X LG Dvd burner with lightscribe for $0.50 more. It's slightly faster than the one you have.
An article/review somewhere that I read not long ago made me take a mental note of the earthwatt series of PSU. Cannot remember exactly where I saw it, but I do remember distinctly what the note I made was.
That note sticking in the back of my head is "don't ever buy one of them"