I live in the midwest where temps can get pretty darn cold (ok so its not Minnesota or Manitoba). I had one vent (pre-existing) in the basement. I insulated the walls. The floor has an 8 pound pad under tight-looped berber carpet. When the furnace is on it almost too warm down there! Its very comfortable. A side benefit to finishing the basement - my heating bills went down! I'm saving $30-50 / month in the winter over previous years. Its a great room for the kids to have friends over.