I would use tables. Put the header in a colspan=2 at the top, and the sidebar into a small td at the side. ie:
<table>
<tr><td colspan=2> <? include("header.php"); ?>
</td></tr>
<tr><td width=25%><? include("sidebar.php"); ?>
</td>
<td>
body goes here
</td>
</tr>
</table>
Or something similar.
moonie 😉