This is an example showing how to make min-width work in IE. The goal is to use as few extra divs as possible and the example is a slimed down version of Stu Nicholls min-width method.
Try resizing the window. You will see that you can't get the div marked with a red border any smaller than 500px. Tested in Firefox 1.5, Internet Explorer 6 and Opera 8.52.