sure...
The enclosing-thing is another table, consisting of an upper part (header and top left and right corner part, and the first piece of the bottom left corner + cell for enclosing the forum-output) and a lower part (bottom right corner + row with horizontal left and right corner parts + <br> for separating the forums)
The HTML goes like:
<table width="100%" border="0" cellspacing="0" cellpadding="0" background="images/hdr_bg_b.gif">
<!-- header part -->
<tr>
<td width="8"><img src="images/hdr_t1_1.gif" alt="" height="36" width="8" border="0"></td>
<td width="233"><img src="images/hdr_t1_2.gif" alt="" height="36" width="233" border="0"></td>
<td align="center"></td>
<td align="right" width="243"><img src="images/hdr_t1_3.gif" alt="" height="36" width="243" border="0"></td>
<td align="right" width="8"><img src="images/hdr_t1_4.gif" alt="" height="36" width="8" border="0"></td>
</tr>
<!-- /header part -->
<!-- top corners -->
<tr>
<td width="8"><img src="images/hdr_t2_1.gif" alt="" height="6" width="8" border="0"></td>
<td width="233"><img src="images/hdr_t2_2.gif" alt="" height="6" width="233" border="0"></td>
<td><img src="images/spacer.gif" alt="" height="4" width="4" border="0"></td>
<td align="right" width="243"><img src="images/hdr_t2_3.gif" alt="" height="6" width="243" border="0"></td>
<td align="right" width="8"><img src="images/hdr_t2_4.gif" alt="" height="6" width="8" border="0"></td>
</tr>
<tr>
<td valign="top" bgcolor="#dddddd" width="8"><img src="images/hdr_t3_1.gif" alt="" height="21" width="8" border="0"></td>
<td rowspan="2" colspan="3" bgcolor="#dddddd">
<!-- /top corners -->
<!-- forum-content -->
<!-- bottom corners -->
</td>
<td align="right" valign="top" bgcolor="#dddddd" width="8"><img src="images/hdr_t3_2.gif" alt="" height="21" width="8" border="0"></td>
</tr>
<tr>
<td valign="bottom" bgcolor="#dddddd" width="8"><img src="images/ftr_t1_1.gif" alt="" height="26" width="8" border="0"></td>
<td align="right" valign="bottom" bgcolor="#dddddd" width="8"><img src="images/ftr_t1_2.gif" alt="" height="26" width="8" border="0"></td>
</tr>
<tr>
<td bgcolor="#dddddd" width="8"><img src="images/ftr_t2_1.gif" alt="" height="8" width="8" border="0"></td>
<td bgcolor="#dddddd" width="233"><img src="images/ftr_t2_2.gif" alt="" height="8" width="60" border="0"></td>
<td bgcolor="#dddddd"><img src="images/spacer.gif" alt="" height="4" width="4" border="0"></td>
<td align="right" bgcolor="#dddddd" width="243"><img src="images/ftr_t2_3.gif" alt="" height="8" width="59" border="0"></td>
<td align="right" bgcolor="#dddddd" width="8"><img src="images/ftr_t2_4.gif" alt="" height="8" width="8" border="0"></td>
</tr>
</table>
<!-- /bottom corners -->
<br>
so now that we've got the Code, we'll have to fit it into the Templates...
from "forum home", remove the following:
above $forumbits:
<tr align="center">
<td bgcolor="{tableheadbgcolor}"><smallfont> </smallfont></td>
<td bgcolor="{tableheadbgcolor}" width="80%" align="left"><smallfont color="{tableheadtextcolor}"><b>Forum</b></smallfont></td>
<td bgcolor="{tableheadbgcolor}"><smallfont color="{tableheadtextcolor}"><b>Posts</b></smallfont></td>
<td bgcolor="{tableheadbgcolor}"><smallfont color="{tableheadtextcolor}"><b>Threads</b></smallfont></td>
<td bgcolor="{tableheadbgcolor}" nowrap><smallfont color="{tableheadtextcolor}"><b>Last Post</b></smallfont></td>
<td bgcolor="{tableheadbgcolor}" width="20%"><smallfont color="{tableheadtextcolor}"><b>Moderator</b></smallfont></td>
</tr>
after <!-- main -->:
<table cellpadding="{tableouterborderwidth}" cellspacing="0" border="0" bgcolor="{tablebordercolor}" {tableouterextra} width="{contenttablewidth}" align="center">
we'll have to put our custom code in forumhome_forumbit_level1_nopost (and level2 if you have any level2 forums) and therefore we'll have an ending table part right at the top, which means, that you'll have to put something above that in another "border-table" as well (I did that with the standard-header, but you might want to move up the logged in users bit or whatever), so I altered the Main Template like this:
{htmldoctype}
<html>
<head>
<!-- no cache headers -->
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="no-cache">
<meta http-equiv="Expires" content="-1">
<meta http-equiv="Cache-Control" content="no-cache">
<!-- end no cache headers -->
<meta name="keywords" content="vbulletin,forum,bbs,discussion,jelsoft">
<meta name="description" content="$bbtitle is a discussion forum powered by vBulletin. To visit the forum, go to $bburl/ . To find out about vBulletin, go to http://www.vbulletin.com/ .">
<title>$bbtitle - powered by vBulletin</title>
$headinclude
<script src="fade.js" language="Javascript"></script>
</head>
<body>
$header
<br>
<!-- border around top-bit -->
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="8"><img src="{imagesfolder}/thd_t1_1.gif" alt="" height="7" width="8" border="0"></td>
<td width="233"><img src="{imagesfolder}/thd_t1_2.gif" alt="" height="7" width="59" border="0"></td>
<td></td>
<td align="right" width="243"><img src="{imagesfolder}/thd_t1_3.gif" alt="" height="7" width="59" border="0"></td>
<td align="right" width="8"><img src="{imagesfolder}/thd_t1_4.gif" alt="" height="7" width="8" border="0"></td>
</tr>
<tr>
<td valign="top" bgcolor="{pagebgcolor}" width="8"><img src="{imagesfolder}/hdr_t3_1.gif" alt="" height="21" width="8" border="0"></td>
<td rowspan="2" colspan="3" bgcolor="{pagebgcolor}">
<!-- standard code for top-bit -->
<table cellpadding="0" cellspacing="1" border="0" bgcolor="#535150" width="100%" align="center">
<tr><td>
<table cellpadding="10" cellspacing="0" border="0" bgcolor="#B9AD8F" width="100%">
<tr>
<td>
<!-- text -->
<table cellpadding="2" cellspacing="0" border="0" width="{contenttablewidth}" {tableinvisibleextra} align="center">
<tr valign="top">
<td><img src="{imagesfolder}/vb_bullet.gif" border="0" align="middle" alt="$bbtitle : Powered by vBulletin version $templateversion">
<normalfont><b>$bbtitle</b></normalfont></td>
<td align="right"><smallfont>$welcometext<br><b>$newposts</b></smallfont></td>
</tr>
</table>
<table cellpadding="2" cellspacing="0" border="0" width="{contenttablewidth}" {tableinvisibleextra} align="center">
$unregwelcomemessage
<tr valign="bottom">
<td><smallfont>
Members: $numbermembers, Threads: $totalthreads, Posts: $totalposts<br>
Welcome to our newest member, <a href="member.php?s=$session[sessionhash]&action=getinfo&userid=$newuserid">$newusername</a>
</smallfont></td>
<td align="right"><smallfont>
The time now is $timenow.<br>
You last visited: $bbuserinfo[lastvisitdate].
</smallfont></td>
</tr>
</table>
<!-- /text -->
<!-- /standard code for top-bit -->
</td>
</tr>
<!-- main -->
$forumbits
<!-- end of last "custom border-table" -->
</table>
</td></tr></table>
</td>
<td align="right" valign="top" bgcolor="{pagebgcolor}" width="8"><img src="{imagesfolder}/hdr_t3_2.gif" alt="" height="21" width="8" border="0"></td>
</tr>
<tr>
<td valign="bottom" bgcolor="{pagebgcolor}" width="8"><img src="{imagesfolder}/ftr_t1_1.gif" alt="" height="26" width="8" border="0"></td>
<td align="right" valign="bottom" bgcolor="{pagebgcolor}" width="8"><img src="{imagesfolder}/ftr_t1_2.gif" alt="" height="26" width="8" border="0"></td>
</tr>
<tr>
<td bgcolor="{pagebgcolor}" width="8"><img src="{imagesfolder}/ftr_t2_1.gif" alt="" height="8" width="8" border="0"></td>
<td bgcolor="{pagebgcolor}" width="233"><img src="{imagesfolder}/ftr_t2_2.gif" alt="" height="8" width="60" border="0"></td>
<td bgcolor="{pagebgcolor}"><img src="{imagesfolder}/spacer.gif" alt="" height="4" width="4" border="0"></td>
<td align="right" bgcolor="{pagebgcolor}" width="243"><img src="{imagesfolder}/ftr_t2_3.gif" alt="" height="8" width="59" border="0"></td>
<td align="right" bgcolor="{pagebgcolor}" width="8"><img src="{imagesfolder}/ftr_t2_4.gif" alt="" height="8" width="8" border="0"></td>
</tr>
</table>
<!-- /end of last "custom border-table" -->
<br>
<table cellpadding="{tableouterborderwidth}" cellspacing="0" border="0" bgcolor="{tablebordercolor}" {tableouterextra} width="{contenttablewidth}" align="center"><tr><td>
<table cellpadding="4" cellspacing="{tableinnerborderwidth}" border="0" {tableinnerextra} width="100%">
$loggedinusers
$birthdaybits
$pminfo
</table>
</td></tr></table>
<!-- /main -->
<br>
<!-- timezone/login-->
<table cellpadding="2" cellspacing="0" border="0" width="{contenttablewidth}" {tableinvisibleextra} align="center">
<tr valign="top">
<td><smallfont>$timezone</smallfont></td>
<td align="right">$logincode</td>
</tr>
</table>
<!-- /timezone/login -->
<br>
<!-- icons -->
<table cellpadding="2" cellspacing="0" border="0" width="{contenttablewidth}" {tableinvisibleextra} align="center">
<tr>
<td align="center">
<img src="{imagesfolder}/on.gif" border="0" alt="On" align="absmiddle">
<b><smallfont>New posts</smallfont></b>
<img src="{imagesfolder}/off.gif" border="0" alt="Off" align="absmiddle">
<b><smallfont>No new posts</smallfont></b>
<img src="{imagesfolder}/offlock.gif" border="0" alt="Closed Forum" align="absmiddle">
<b><smallfont>A closed forum</smallfont></b>
</td>
</tr>
</table>
<!-- /icons -->
$footer
</body>
</html>
after that we'll modify the forumhome_forumbit_level1_nopost...