Agree with Ct1615 but get one with 4 PCI-E connectors, ( like the one he linked to), hooking up dual cards with molex/PCI-E adaptors makes a real mess of the interior and can effect cooling airflow-The last thing you want to do with a SLI rig.
And from Seasonic we have:
What about a Cooler Master Pro Modular M1000W Power supply? this should be more than sufficient to do the job?
Yes this will do it, As mentioned it will be quite overkill, however I'd recommend this because in future, when the time comes to upgrade again the next series of cards may have higher TDP's etc. and even with power supply degradation it should keep up for years to come.
Other than that, that XFX looks pretty sweet. Definitely worth a look at if you stick with the 650w modular line of thought.
ok heres the thing about GTX 460 SLI and PSU's ( im speaking from experience here). I was also asking people if my OCZ StealthXTream 2 80+ 700W PSU was sufficient to run in sli, and everyone said "go for it, its more than enough, you need 600W psu to run in sli without any problems". So i listened to these folks, got another card and ran vantage to test it out...well, my computer restarted after a couple of minutes. What you have to remember is that all power supplies DO NOT RUN AT 100% efficiency. So in other words, my 700W 80+ psu was a 560W in real life..After that, i bought a corsair 850W SLI 80+ Bronze PSU, and voila, no more crashes, restarts, everything stable. BTW my i7 is OC to 4.0GHZ, so if you have an overclocked cpu-that will draw ever more power from the psu- therefore i highly suggest getting a better-higher WATT PSU