IMHO, i would stick with the X800 and get the Non SLI board, the PCI-E/SLI is still very expensive for what it is

I would wait around for a while(1yr) as the kit will get better and cheaper.

The card you have at the moment is a good one, and will run anything you throw at it at the moment, so i would stick with it and then save up over the next year to buy some serious PCI-E/SLI kittage