Need help hand coding website/ css div issue

i'm trying to hand code a site for a computer club that i participate in. i have an interesting issue that i'm not sure how to solve. the site is www.repairandshareclub.com.

my site is split into three major divs. the header, the middle (or content), and the footer. the header and footer are fixed heights.

right now, the content on my site is set to be a fixed min-height. the problem i am having is that i want the middle div to stretch vertically to fill the visible screen area, or expand past it with the content. so far, if i set these middle divs to 100% instead of some min-height in pixels, the divs only stretch to the end of the content, and not to the end of the visible page.

thanks for any help or ideas!

p.s. the middle div includes the content and a links bar on the left. i would like both the links and the content to expand together.