Stretch Divs to Bottom of Page - 960gs

I’ve almost finished one of my first sites using 960gs, but I’m struggling to find a way to get the bottom boxes in each column to stretch down to the footer so that the bottoms all line up.

Here is the page:

And this is what I am trying to do:

The content of each box comes from a CMS, so I cannot give the boxes fixed heights.

Even if I can somehow give the illusion that the boxes line up, that would be great. Any ideas?

Hi i am newbie and facing the same problem still to be solved , waiting for some solution.