Meh, I'm a fan of AMD myself, and AMD usually are cheaper, and have more special offers, but your choice.
Just to give an idea of RAM imporance. I have a GTX 280, for few days I only had 2GB RAM, I benchmarked it. When I increased it to 4GB it doubled the Graphical Capability.
However, remember the law of diminishing returns, eventually you will be paying tens of thousands of kronos or whatever just to get a 1fps increase.
However, Ted's idea of a setup looks pretty good.