It looks like a solid build, but here's what I would do differently:
Switch the HDD to a WD Caviar Black 1TB. (or better yet: two WD Caviar Black 640GB in RAID 0, if you can budget for them) The drive you selected is way overpriced IMO; you'll probably get better performance from the WD anyway.
That video card might be a little bit of overkill at 1680x1050. I'd consider lowering it to a 4870. You probably won't even notice a difference.
Dont get a caviar black 1TB (a caviar black 640 would be great, though - different platters). You just picked the wrong Samsung. You want the Samsung F3 1TB for a gaming machine, not the F1 which is designed for corporate data servers.