Multi-layer elements in HTML Email for Outlook 2007 and 2010
<table>
    <tr>
      <td></td>
      <td valign="top" rowspan="2" style="padding-left:7px;padding-top:17px">
        <img src="path/to/image.jpg" />
      </td>
  </tr>
  <tr>
    <td colspan="2">
        <img src="path/to/image.jpg" />
    </td>
  </tr>
</table>