You didn't give a budget so I will assume money is no object
Asus Rampage II Extreme - $329 w/ $30 rebate
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131352
Why - Great Power regulation, superb cooling, great features and it just looks so damn cool
Look at the i7 offerings from Gigabyte, MSI and ASRock if feeling the budget crunch.
Mushkin Redline 3 x 2G DDR3 1600 w/ 6-7-6-18 CAS timings $ 212.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16820226052
Why - lowest timings on newegg for DDR3 1600
Look at Corsair XMS, Gskill Ripjaws and the OCZ higher end stuff....don't see a reason to go above DDR3 1600.
Sound Card - The daughter card that comes with the Rampage II Extreme
Instead of the 5870, I'd recommend twin 5850s, not that I think the 295 GTX is a bad choice, much more so though if you are the type that doesn't keep a GFX card more than 2 years. It won't do DX11, but very little will for the next 18-24 months....and it's not as though DX10 has shook the world. Here's some choices you might consider:
a) GTX 295 if buying today and gonna keep for 2 years or less and/or you think PhysX is appealing.
b) Twin 5850's if you think you need DX11 or keeping the cards for > 2 years.
c) Twin 5850s w/ a dedicated PhysX card (i.e 9800 GT or better) if you stuck between a) and b)
d) Sit around till between Thanksgiving and XMas and see what shakes outta nVidia's tree (and the impact it has on other cards prices) before deciding
I'd be hard pressed to find fault with any of the above.