I don't think that 550w would be enough, sorry.
Many PSU calculators are very complicated, but I have managed to find a really simple one from ASUS:http://support.asus.com/powersupply.asp
This seems to work quite well, but I'm not sure it is 100% accurate. I would add 50w to whatever recommendation you get just to be on the safe side.
When I ran your build in the calculator, it came out as minimum
550w, and then with the 50w added for error, I would say that a 550w PSU would not be enough. I would get a good Corsair or Cooler Master 650w PSU just to be safe