I"ve tried a few things and failed to recreate this layout using frames with CSS:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Untitled Document</title>
<frameset rows="200,*" frameborder="no" border="0" framespacing="0">
  <frame src="header.html" name="topFrame" id="topFrame" title="topFrame">
  <frameset cols="50&#37;, 50%" frameborder="no" border="0" framespacing="0">
    <frame src="left.html" name="leftFrame" id="leftFrame" title="leftFrame">
    <frame src="right.html" name="rightFrame" id="rightFrame" title="rightFrame">
So, it's a 200px high header and then two main sections with scrollbars that occupy the remaining space.
It's just getting the 100% - 200px height for the content boxes and not losing the scroll bars which I am having trouble with.