Looks like you’re going in the right direction with the div layout there. However, we might want to take a look at the actual design of the manager first. Reason is that if the design calls for a footer to float down to the bottom then the proposed layout might be a little quirky from a CSS point of view. In alot of case, I’ve grown accustomed to wrapping most of my divs with a container div, like so:
<div id="cms_container">
<div id="cms_header">[+header+]</div>
<div id="cms_menu">[+menu+]</div>
<div id="cms_sidebar">[+panels+]</div>
<div id="cms_content">[+content+]</div>
<div id="cms_footer">[+footer+]</div>
</div>
If you look at the code for the CSS Zen Garden site, you’ll notice that just about all of the divs are wrapped with a container div (except for the extra blank divs at the bottom). The benefit of this is that you can define the container div to be a relative height to the body tag, which more or less allows you to easily float a footer or some other div to the bottom of the page. There is a trick to it...mostly involves the use of the min-height definition in your css.
At any rate, a container div is a good idea because it offers much more flexibility in the longrun.