Good to see you have gone for more RAM :P

If this rig is going to primarily be for multiboxing the other I would consider a couple of changes. GTX280 is probably overkill even for a 30 inch 2560 X 1600 setup. You could back off to a GTX 260 easily or 4870 for about half the price.

The other thing to consider would be RAM. DDR3 is expensive and you don't really need the speed, just the volume. You could get a P45 motherboard and 4 x 4GB DDR2 RAM for less than your existing specs which would be more effective as well as cheaper.

I know this board doesn't SLI for future use but you could always grab a 4870x2 if you wanted more power in the future (or whatever else AMD/NVIDIA comes up with for their next dual core board).

Cheers