I commute year-round in Madison WI. Since it's "only" commuting, and I don't sweat a lot, I don't really need an elaborate system. I wear snow pants over my regular work pants, hiking boots, a ski jacket, and ski mittens. I have a neoprene face mask and a beanie that goes under my helmet. At the coldest temps (i.e., below zero), I might add a sweater and switch to my downhill ski helmet and goggles. A ski helmet is typically not ventilated, and has built in ear muffs, so it's much warmer. There are always a few other cyclists on the paths, and most seem pretty happy to be out there.

I think it's important to get acclimatized gradually. Don't try to start winter riding for the first time in mid January. The same temps that seem cold in December will seem warm in the spring.