At that resolution, if I had 2k to build I would definitely go with the Evga gtx 275, Cheapest one I can find, and then I would SLI them. a Tx850 would be cheaper so drop back to the TX version so you have money to get a second card. of course this is all without even thinking about the future.
Why? What is the reasoning for going with the dominator ram? The 850HX is a very good PSU and the modular aspect will help keep your case clean. I doubt you will need a second card for a while, a single GTX 275 will work fine for a while, by the time it doesnt the DX11 cards will be out.