That newegg PSU calc is quite possibly the least accurate thing ever invented, i just plugged in my config and it says i should have a 549W unit, im running on an Earthwatts 500W unit and my system only breaks 350W occasionally.
As for what size PSU you need for something like that, since nVidia decided to ignore the 300W power limit rules of thumb no longer apply, i would get at least a good 750W unit for the GTX 590, but if you are planning for a 1100T and a 590 you might want to consider an i7 2600K and 2 GTX 570s instead, they will run a lot cooler and cost less.
I'm not looking forward to SLI because of past experience but I want to take advantage of the phenoms 2 extra cores but I prefer just one Video card because I heard from my friends that ATI is better than Nvidia when with 2 or more but nvidias best by itself and less of a hassle.
I basically want a simple (Simple in which there's no prob with games or multitasking) PC
Although correct me if I'm wrong...