If you don't use forum discriptions then use:
Code:
<tr id="cat">
<td bgcolor="#336D95" background="https://vborg.vbsupport.ru/images/catagory_backing.gif" colspan="6"><a href="forumdisplay.php?s=$session[sessionhash]&forumid=$forum[forumid]"><normalfont color="#000000"><b>$forum[title]</b></normalfont></a></smallfont></td>
</tr>
Untested but should be nearer to what you want or the same height as the others.