thats the way i would do it, use the header to open the left column and the footer to handle the right column.
content is placed between the two (the middle)
Header: open and find at the bottom the start on the table that contains the main content, above that add the 1st cell (left column) and the table
HTML Code:
</td>
</tr>
</table>
<table border="1">
<tr>
<td><!-- new table cell -->
<table align=center border="1">
<tr>
<td>right handside</td>
</tr>
</table>
</td>
<td> <!-- main content -->
<div align="center">
<table width="100%" border="2">
<tr>
<td>
Footer: Insert new table cell at the top
HTML Code:
<td valign="top"><!-- new table cell -->
<table align=center border="1">
<tr>
<td>right handside</td>
</tr>
</table>
</td>
</tr>
</table><!-- end main content -->
Hope that's right as it was from memory, hope it helps