Performance has some good deals on winter gear. At minimum I'd get:
long finger gloves
wicking base layer (long sleeve)
long sleeve jersey(s)
Wind jacket
arm/leg warmers and/or tights
warm socks (I like the Defeet Blaze wool)
Toe covers for shoes (blocks all those vents that are nice in summer, bad in winter)
Head/ear warmer of some sort. Wool is good here as well.