I'm building a site, and I want to have a header and footer that go across the whole page, with a main section that is centered and 900px wide. You can check out the current progress at DesignaCast.com.

When the user makes their browser smaller than 900px they get scroll bars, and if they scroll to the right, there is whitespace where the header and footer should be...does anyone know how I might begin to fix this problem?