i've been riding this winter in 5F-25F degrees this winter in NYC and it's really not that bad, what you have is a mental block.

really, it's all mental. and layering.

layering really needs to be done on the face/head, hands, and feet. two pairs of thick wool socks were enough. hands, two pairs of gloves. head/face: balaclava, skull cap and hood over the helmet. body can be layered but not as aggressively as extremities.

to keep things in perspective, there are people who are riding all winter long in edmonton where it gets much colder. Scandinavian countries. etc.

over snow: studded tires. i plan to get them now for next winter.

a denver cyclist (once from NYC) commutes thru snow recommended this site to check out for cycling in winter conditions:

Icebike Home Page

it's pretty awesome. i've been reading up on more info for next winter.