Been awhile since I've posted, wondering if I can just upgrade my video cards (8800 GTX) to the 600 series.  Dual SLI would be nice.  I figure this will help me last until next year, for my planned upgrade.  Since I'm a bit rusty on the latest and greatest, figured I'd ask for help to make sure.  Here's what I'm  running, the important bits at least:
 
EVGA 780I motherboard with 8 gigs ram (Watercooled, not overclocked atm)
2 EVGA 8800 GTX in SLI mode
Intel Core 2 Extreme QX9650  CPU
Thermaltake Toughpower W0133RU 1200W
Dual Raptors with Windows Vista (yah, i know time to upgrade that too, probably will at the same time)
 
I'm assuming the biggest issue might be power.  Will my current psu provide enough, and are the connectors still relevant?  I also realize that I won't be running the latest game on max, but just want something to tide me over till next year.  The puter is really lagging in some of the recent games that have come out.  Thanks.

 
 

you PSU would be fine, the biggest issue you will have is the MB and CPU, they are really going to hold that 600 card back, even more in SLI. But you will still see a good bump in performance in games, just not as much as the card could offer.

The Core 2 generation was approximately 20% behind even the earliest Core i7-900's clock-for-clock (where the 3.2GHz QX9770 tend to be close to the 2.66GHz i7-920), so you'd have to figure out how to overclock your QX9650 to just around 4.2GHz in order to achieve the performance implied in this guru3d review of GTX670 in SLI since they used a first-gen i7 overclocked to 3.7GHz.
 
Also, GTX670 and 8800GTX both draw around the same wattage, in fact they both have the same 225W limit from the PCIe slot (75W) and each of dual 6-pins (75W each).  You need not worry about your PSU unless capacitor aging has set in-- which is only a problem if your unit is past warranty.