Best 'bang-per-buck' pre-built high end PCs

[Thorsson]

You could try looking at cyber power systems.

They have some good deals over there.

Gamer Infinity SLI 900

That one looks similar to your above spec and is fully customizable.

Yeah but they are charging an arm and leg for a decent PSU and none of the coolers are what I'd choose (and I could go on....).