Ho scritto qualcosina, giusto per farti un esempio pratico.. Spero vada bene (la solita mancanza di tempo mi impedisce di testare )

codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html>
<head>
<title>Untitled</title>
<style type="text/css">
table {
border: 1px solid blue; 
border-collapse: separate;
border-spacing: 1px; 
table-layout: fixed; 
width: 250px;
}
		
td {padding: 3px; 
background-color: #eee; 
white-space: nowrap; 
overflow: hidden;
height: 20px;
}
		
thead td {
font-weight: bold; 
border: 1px outset;
}
		
.mezzo {
height: 100px; 
overflow: auto;
}
		
.mezzo {
width: 267px; 
overflow-y: scroll;
}

</style>	
<div id="sopra">
<table  border="1" summary="Test table for scrollable TBODY table regions">
     <thead>
     <tr>
       <th rowspan="1" colspan="1">Titolo Tabella</th>
     </tr>
   </thead>
</table>
</div>

<div class="mezzo" style="height: 100px; overflow: auto">
<table border="1" summary="Test table for scrollable TBODY table regions">
   <thead style="display: none">
     <tr>
       <th rowspan="1" colspan="1">Riga</th>
       <th rowspan="1" colspan="1">1</th>
       <th rowspan="1" colspan="1">2</th>
       <th rowspan="1" colspan="1">3</th>
       <th rowspan="1" colspan="1">4</th>
     </tr>
   </thead>
   <tfoot style="display: none">
     <tr>
       <th rowspan="1" colspan="1">Riga</th>
       <th rowspan="1" colspan="1">1</th>
       <th rowspan="1" colspan="1">2</th>
       <th rowspan="1" colspan="1">3</th>
       <th rowspan="1" colspan="1">4</th>
     </tr>
   </tfoot>
   <tbody>
     <tr>
       <th rowspan="1" colspan="1">Riga</th>
       <th rowspan="1" colspan="1">1</th>
       <th rowspan="1" colspan="1">2</th>
       <th rowspan="1" colspan="1">3</th>
       <th rowspan="1" colspan="1">4</th>
     </tr>
     <tr>
       <th rowspan="1" colspan="1">Riga</th>
       <th rowspan="1" colspan="1">1</th>
       <th rowspan="1" colspan="1">2</th>
       <th rowspan="1" colspan="1">3</th>
       <th rowspan="1" colspan="1">4</th>
     </tr>
     <tr>
       <th rowspan="1" colspan="1">Riga</th>
       <th rowspan="1" colspan="1">1</th>
       <th rowspan="1" colspan="1">2</th>
       <th rowspan="1" colspan="1">3</th>
       <th rowspan="1" colspan="1">4</th>
     </tr>
     <tr>
       <th rowspan="1" colspan="1">Riga</th>
       <th rowspan="1" colspan="1">1</th>
       <th rowspan="1" colspan="1">2</th>
       <th rowspan="1" colspan="1">3</th>
       <th rowspan="1" colspan="1">4</th>
     </tr>
     <tr>
       <th rowspan="1" colspan="1">Riga</th>
       <th rowspan="1" colspan="1">1</th>
       <th rowspan="1" colspan="1">2</th>
       <th rowspan="1" colspan="1">3</th>
       <th rowspan="1" colspan="1">4</th>
     </tr>
   </tbody>
</table>
</div>
<div id="sotto">
<table border="1">
   <tfoot>
     <tr>
       <th rowspan="1" colspan="1">Fondo Tabella</th>
     </tr>
   </tfoot>
</table>
</div>
</body>
</html>