Motherboard wise I'd get an 890GX right now.
Asus is coming out with an 890FX Crosshair soon from what I've heard, I'd probably buy that on a $1000 budget.
HIS is a great video card manufacturer, I'd say they were on par with Sapphire probably.
At the very least they're magnitudes better than Diamond or Visiontek.
I don't understand why you want to get the Antec Twelve Hundred with your build?
Any particular reason you want a filing cabinet for a case?
Your parts could fit in a small mid tower, why go for a full tower, when you can get a large mid tower for much cheaper.
Also the 750w Antec Truepower New is overkill for a single graphics card.
I'd only get that if you were planning on crossfire in the future.
Also the Samsung Spinpoint F3's offer an alternative to the Caviar Blacks right now, if you're someone who moves larger files around a lot, I'd get the Spinpoint F3's, if you just access a random file here or there though, stick with the Caviar Black.
(The Spinpoints have faster sequential read/write speeds which give them better performance for larger file transfers(Files greater than 300Mb), while the Caviar Blacks have faster random access times making them ideal for accessing smaller files faster.)