CSS Layout Footer Question

CSS Layout + Footer Question?

Alright, so I have a wrapper div.

A header div, and two content column divs (one left, one right) are inside of the wrapper.

I want to add a footer to the whole shabang, so how would I keep the footer at the bottom of the wrapper? How can I make it so the wrapper expands and contracts with the height of the header and the right column? (The right column will always be longer than the left column.) Also, the columns and header div are position: absolute; - is this a problem?

Thank you very much and I WILL choose a best answer quickly.