Endless debate in the winter cycling forum about that !

I use some Specialized glove within a glove gloves for my hands and some Keen winterport boots (several sizes too large to avoid any compression of the two pair of socks I wear -- one thin wool (Smartwool type) and one bulky wool (Wigwam type)). I like the winterport boot because its unusual in that its really more of an insulated shoe with an integral gaiter, so nothing rubs from the ankle on up. If there is really bad headwind where I'm looking at 75+ minutes, I'll sandwich one of those chemical warmer packs between the pairs of socks over my toes. I'm generally good for 60-65 minutes at 5F before wanting the chemical warmers.