3 column with footer problem

HI... I'm new to css and I'm using dreamweaver for editing it and here is my problem:

My site is not yet online but basically here's the concept of design... There is a navigation menu on the left, content in the middle and a sort of "what's new" on the right and a footer wich should have a banner and some other stuff. My problem is that I dont know how to keep the borders of my navigation and "whats new" always connected with the footer no matter how long is the text in the content.

Is there a way the border of these 2 could always ajust to the height of the center page ? It makes no sense that I should always bother with setting their height. Please help.. thanks.