Halfway through upgrade, suggestions?

I just got the Asus Sabertooth x79 and a 3930k cpu, Corsair Dominator 4x8gb kit (Which DOES NOT work without using the "MEM-OK" Button to find safe default timings), and a Cooler Master TPC 812 cooler. I am running these with a Cooler Master 650W power supply and an ATI Radeon 4870 from the previous setup. I have been looking at either the 7950 3GB ATI card or a pair of 6870's in Crossfire. I am leaning towards the 7950 as I can always add another later when they are cheaper to upgrade again without throwing away the card. Will the 650W cooler master handle the 7950 and the other hardware I have ok? Or should I upgrade that too to be safe. I was looking at an Enermax Platinum 1200W, but, already spending too much, wouldn't mind holding off on that til later. Might just save my life from my wife… lol. I have three HDDs, (2 standard sata + 1 64GB SSD) and a DVD Burner also. Thanks.

Actually, using one of the many online power supply calculators your system will only need 400W at 90% load.

Go to dual 6870's and expect to require 500W, still within the limits of your existing power supply.

These are "recommended" limits, and are higher than the actual expected load will be.

I have yet to see any system with a need for such a large power supply. I think its a bit of a myth. I would not trust the calculator totally and would add an extra hundred watt safety zone which is still within the limits of your power supply in both configurations you mentioned. So you are absolutely fine.

Its arguable if putting in a larger power supply extends the life of the power supply by reducing its overall load.

Here's the calculator I used: http://extreme.outervision.com/psucalculatorlite.jsp