Dual GTS 640MB, what PSU? Or Nvidia 9 Series

I currently have an Nvidia Geforce 8800 GTS 640MB, 4GB DDR2 RAM and a Q6600 Processor.
If i was to upgrade to Dual 604MB GTS's, what would you recommend for the PSU?
I currently have a 650W, but surely i would be required to upgrade to around 1000W if i wanted Dual GTS's?
I want an upgrade as i have recently purchased a 1920x1200 monitor, and am now struggling at the high resolutions on games.
After reading the sticky as the top of this section, i believe it is impossible to pair a GTS with a GTX, or at least not advised?
Also, i recently read somewhere that it will only be a month or two until the new Nvidia 9 series cards come out; greatly knocking down the prices of the 8 series. Would it be suggested to get the, what will be cheaper, dual GTS 640MB, or upgrade to a single mid-range nvidia 9 series card as these will be far more powerful.
Basically i require some advice for my scenario.
It would be much appreciated!
Thanks,
Sabre_X

If you havent loaded up your system with a bunch of extra goodies a 650W PSU should handle 2x 8800GTS in SLI.
If your PSU has +12 Volt current rating of 30 Amps I don't think you'd need to change PSUs.

Until you see some actual performance reports for the new GPUs & pricing changes for GTS/640 I'd hold off making any decisions. So far I can't see that the prices have dropped off all that much for GTS/640.

For right now I'd roll back the quality setting till you get acceptable performance, or reduce game resolution (ie 1680x1050 in windowed mode) until you know enough to make up your mind what you want to do.