I'm wondering if it is possible to have a header div and a content div (or iframe) and have the content div (or iframe) be 100% height minus (-) the height of the header. I hate using tables, I know you could do it that way but they are just a nightmare. Same with framesets, which I know could also achive this.
One way you may be able to get what you want is to position the header div absolutely and give the content div padding-top equal to the height of the header.
Hope that helps