How to set limit to the window width

I have a 3 column CSS. When I resize the windows to smaller size, the
left and right column width are not change, but the middle column will
shrink.

What I want to do is to set a limitation to the middle column (set min-width)so it can shrink only up to certain width said 100px. so when I keep shrinking the windows until really small, I have to scroll left and right to see the content. And I am using IE6.

Eg, www.mywebhome.ca

Please advice. Thanks.