Prova cosi.... con IE

codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>
<head>
<title>Untitled</title>
<script language="JavaScript" type="text/javascript">
<!--
function hideShow() {
 if (oDiv.style.visibility== 'visible') {
  oDiv.style.visibility = 'hidden';
	oBtn.value            = 'Show';
 } else {
  oDiv.style.visibility = 'visible';
	oBtn.value            = 'Hide';	
 }
}
//-->
</script>

</head>
<body>
<div style="visibility:hidden" id="oDiv">
 <table summary="">
  <tr>
   <td>Uno</td><td>Due</td><td>tre</td>
  </tr>
  <tr>
   <td>Uno</td><td>Due</td><td>tre</td>
  </tr>
  <tr>
   <td>Uno</td><td>Due</td><td>tre</td>
  </tr>		
 </table>
</div>
<input id="oBtn" type="button" value="Show" onclick="hideShow()">
</body>
</html>