[Neko]

I have a very very similar setup. The Sonata III is a really nice case and looks really good imo. I'd second NU Star's suggestion of getting the Raptor HD, PT imports seem much snappier with it. You don't need the more expensive Raptor X that NU linked to. If you don't care about seeing inside the drive just get the regular Raptor.

Sonata III comes with a decent 500W power supply so not sure if you really need to upgrade it.

The one other thing I would suggest is to go to an aftermarket cpu cooler as the stock intel one is kinda loud. I got a Zalman ultra-quiet cpu cooler, which was a bit of a pain to get installed, but it has an externally adjustable fan. On the lower settings my computer is practically silent. It's so sweet to not have to listen to your computer all day.