Well, I hunt the first week of November in the mountains of Colorado so it's pretty cold. Last year I used a base layer of Smart Wool. The stuff worked great. I wore the top, bottom, and socks, with a liner and I stayed warm down to around 0 degrees.

This year I am going to try the Under Armour. I have heard a lot of good things about the cold weather Under Armour, and would like to try it. I was at one of the sporting goods stores yesterday and priced the Under Armour and the cold weather top is $49, and the bottoms were $49. Worth every penny if it keeps you warm and dry.