you probably won't need quad rails unless you are running a dual cpu setup or the new dfi expert board that ueses the 8pin 12v atx plug instead of the 4pin.
it is not so easy to always tell which outputs/plugs are on which rail. a dual rail psu will typically have the cpu and gfx card/s on one rail and everything else on another rail. when there are 3 rails typically the first two are for the cpu/s (often the second rail is for the 2nd cpu and if you don't have 2 processors the rail may go to waste)
quad rails are unnecessary. it may help some with stability, but you really aren't going to see a difference between a quality dual rail psu and a quad.
if you want a silverstone, the zeus is a bit more powerful and more tested.
I would highly suggest the Seasonic S12-600. it is just as powerful as the psu you were looking at, it's more efficient and quieter.
This is also a very good psu that I have heard nothing but good about. it also has quad rails, sleeved cables and high efficiency, low noise