I have a vent in the ductwork coming off my furnace in the basement. It is currently closed. I figure it doesn't make much sense to heat an area of the house I hardly ever use. Would it be cheaper to leave it open? Would heating my basement help heat the rest of my house somehow?

(I live in Wisconsin...temps are in the single-digits right now...very cold....furnace runs a lot.)

I should add that my basement is not finished. Concrete floor and very old (50 years) stone basement walls.