Two 1GB cards in SLI/Crossfire would be appauling for a resolution that high, you'd fill that up even at 1080p. Much better off just getting a 7950, its a little more expensive than two of those, but it has a 3GB frame buffer, so it is more than capable of driving 3 screens. Not to mention its massively faster, and would actually provide enough performance for that resolution to be viable.
You also need to factor in the 650 can't sli!!! I wouldn't recommend cfx for the 7770 either because it will provide more horsepower than that amount of ram can handle. You're better of with a 7850 that you can upgrade later. You could also get a 7870.
If i upgrade the cards to 2 gb ram each, so 4 gb total, would that help?
No. SLI utilizes alternate frame rendering, two 2GB cards don't equal a total of 4GB available VRAM, as one card still has to store all the data for one frame, and the other card for the next, and so on.
Agreed you can not SLi a 650 or 650Ti. I would not go with a 7770 in crossfire as well. Stability and performance wise both solutions are incomparable to a single gpu solution. A GTX660Ti if you go with nvidia is a good solution which to my thinking would probably be what a 650Ti would be in SLi. And a 7850 is a good chip as well in line with the GTX660. In the end you will be much happier with a single GPU solution Caleb.