Please, buy the best book on winter camping ever.
"Allen & Mike's Really Cool Backcountry Ski Book"
OK, so maybe 1/3 of it is on backcountry skiing but the rest is on winter camping and clothing. I used to teach winter survival to US Army ROTC cadets, including a weekend winter bivouac so this is part of my basis for recommending this book.
My layering advice:
BASE LAYER> Cabela's sells a vast assortment of goood synthetic base layers. Unless you live south of the Mason-Dixon Line and below 4,000 feet get at least a medium weight set of longies.
MID LAYER> synthetic or fluffy Merino wool sweater
INSULATING LAYER> A good synthetic puffy. The North Face appears to have a good new layer with its Puff Ball insulation. Taking along insulating pants will, when used with the jacket, greatly extend warmth of your sleeping bag. Dress for sleepng before cooking dinner and you'll be warmer for the more sedentary camp chores.
(Down jackets and pants are nice for camp but get damp from travel exertions.)
(Pile or fleece is OK but heavier than shelled synthetic insulation and much bulkier to pack.)
OUTER LAYER> You have two choices:
1. Softshells W/ windproof membrane and good DWR treatment
2. WPB hardshells like eVent or Gore-Tex Pro Shell (not "regular" GTX).
I prefer my REI Kimtah eVent suit. It's lighter and far more compact than softshell outer layers and almost as breathable but totally waterproof. I recommend a good parka, not a mere jacket.
HEADGEAR> A nice "Inca" style wool knit hat with fleece liner is good for both day and sleeping. "Everest"brand made in Nepal is a good one. You WILL need a warm sleeping hat or balaclava. Your sleeping bag's down hood is not enough as your head will turn inside it and be exposed when you move around in your sleep.
FEET> base layer-> thin poly liner socks (synthetic dress socks are fine)
insulating layer-> I prefer thin closed cell neoprene diver's socks which I have seam sealed. They are THE VBL, keeping sweat from ruining your boots' insulation and provide great insulation as well.
BOOTS> try for GTX lined boots to keep water from entering from the outside.
GLOVES> GTX outer shells with TWO or more removable fleece liners of medium and thick fleece to vary acording to temnperaures. Buy the gloves with one pair of liners they come with then go find another pair of fleece gloves to fit the shells.
Mitten shells for very cold situaions where you use your warmest glove liners.