I've been following and reading reviews at tomshardware.com and frankly I wonder if there is much performance gain past 1GB of video memory. You may want to reconsider this and pick from tomshardware's lists of best video card for the money and don't get sucked into some idea that more ram equals more performance.

Let the benchmarks help you.

And a nod to the pair of memory sticks. One of the nice side effects of keeping it down in count is less loading on the memory and address bus. Yes, that means more speed and stability.
Bob