those kind of winter cycling jerseys are quite good. just make sure you get one that fits snug- it's got to be flush against your body/layers underneath. If you were to wear one of those thin little Defeat undergarment sweat layer things (sold at MEC), with two normal skin-fitting short sleeve jerseys, and then this CSC thing, you'll be warm until it gets a couple degrees below zero. Be forewarned that if you stop mid-ride for a coffee, strip off your layers ASAP.

But that's just what works for me. Every body reacts differently when playing in the cold.