I'm considering getting another cheap gtx260 for sli in the near future - what sort of PSU would be recommended for this - I think my current seasonic 600watt would probably do it (just....) - but probably not comfortably....
The Intel rig in my sig draws 400 watts from the wall (24" monitor included, I was too lazy to unplug it) while burning linpack + furmark, so you'll be fine.