column height = always equal?

I have a two column design sort of like the design of this page, but my problem is that sometimes my “menu” column is longer than my “content” column, and while the “content” column stops, the “menu” column just proceeds on down the page!
Is there any way to make the height of the shorter of the two always at least the height of the tallest one?
Thanks…
My page is here and here is an example of what I’m talking about.
~T