Where to buy this Mobo?

Newegg has it too...

http://www.newegg.com/Product/Prod [...] 6813128471

I am sure of that : )

It will NOT make a big difference. Just get something like an MSI Z68A-GD80. That's a great OCing board, and it's $190 after rebate. http://www.newegg.com/Product/Prod [...] 6813130610

Get a good 750W PSU for 7970 SLI, like this one, $120 after rebate: http://www.newegg.com/Product/Prod [...] 6817256059

Any old optical drive. Here's one that's fine: http://www.newegg.com/Product/Prod [...] 6827136240
or a BDD if you want one. A black one or a silver one.

A $70 Hitachi 500gb, or a $110 WD Caviar Green 1tb if you think you need the space. You probably don't if you go with the big SSD.

I think you can afford a 256gb SSD. If you think you've got the cash for a Sniper, then put it here instead. I support the $305 ADATA S501 256gb. If you don't want to spend that much, then get a $145 Patriot Pyro 120gb.

You really don't need liquid cooling. The 7970 is quite loud, so your CPU cooler's noise will be totally hidden, and Sandy Bridge doesn't have big temperature problems. I'd go with a $50 Scythe Mugen 3.

Choose your case by stylistic preference. Most full-ATX cases over $60 will work fine. Just trawl Newegg and see what catches your eye.

The NIC doesn't matter at all (absolutely no difference), and IMO the sound card doesn't either. There are some that would argue that you can hear a difference on high-end audio equipment (do you have any?), but I haven't found anyone willing to do a blind test.

You don't need SLI yet, but you'll be able to add another 7970 in the future when one is no longer enough. The single card should max all current games on 1920x1080. By the time you want another one, the price should have gone down a little.

Don't bother spending extra on the Caviar Black. Your system drive will be an SSD, which is worlds faster than any hard drive, and the only files on your mechanical hard drive will be ones for which speed is not important (music, documents, etc).

Why Do You Insist On Capitalizing All Of Your Words?

Yes, starting with the OS. Use the SSD as your main drive, installing Windows, games and other programs that benefit from extra speed (Photoshop, for example). Put other stuff on the HDD. Put your documents on the other drive, and the iTunes media folder as well. You can point iTunes at a folder on any drive.

Yes. It will take some management, but it's definitely doable. I'm running on a 120gb Corsair Force GT right now, and I've got about 50gb free with several major games, Photoshop and Windows.
A $305 256gb ADATA S501 ( http://www.newegg.com/Product/Prod [...] 820211530) would be very nice, of course, if you feel like you can afford it.