[B]this is inside submenu[/B]
<a href="http://forum.lowyat.net/topic/1339427" onclick="changeContent('image_frame', 'http://www.google.com.my/logos/olympics10-sskating-hp.png');" target="content_frame">Link 1</a>

<script>
function changeContent(targetFrame, content) {
     top.frames[targetFrame].location.href = content;
}
</script>

function dw_loadExternal(url, ifrmId, divId, bLoadMsg) {
   // defaults for iframe, display div
   ifrmId = ifrmId || 'buffer'; divId = divId || 'content';
   if ( window.frames[ifrmId] ) {
       // Could use location.replace method if you do not want back button to load previous iframe url
       //window.frames[ifrmId].location.replace(url);
       window.frames[ifrmId].location = url;
       // If you want the whole page to scroll to the top when new content is loaded
       //window.scrollTo(0,0);
       var lyr = document.getElementById? document.getElementById(divId): null;
       if ( lyr && bLoadMsg ) { // Option to display message while retrieving data
           lyr.innerHTML = '<p>Retrieving data. Please wait ...</p>';
           lyr.style.display = 'block';
       }
       return false;
   }
   return true; // other browsers follow link
}


// called onload of iframe
// displays body content of iframed doc in div
// checks for and invokes optional functions in both current document and iframed document
function dw_displayExternal(ifrmId, divId, fp) {
   // defaults for iframe, display div
   ifrmId = ifrmId || 'buffer'; divId = divId || 'content';
   
   var lyr = document.getElementById? document.getElementById(divId): null;
   if ( window.frames[ifrmId] && lyr ) {
       lyr.innerHTML = window.frames[ifrmId].document.body.innerHTML;
       lyr.style.display = 'block';

       // when using with script, may have some operations to coordinate
       // function in current doc or iframed doc (doOnIframedLoad)
       if ( typeof fp == 'function' ) {
           fp();
       }
       
       // Demonstrated in tooltip demo
       if ( typeof window.frames[ifrmId].doOnIframedLoad == 'function' ) {
           window.frames[ifrmId].doOnIframedLoad();
       }
   }
}

/*CSS*/
#buffer { position:absolute; visibility:hidden; left:0; top:0 }
#content {
   margin: 2em 1em 2em 0;
   border: 0;
   padding:6px 8px;
   display:none; /* until loaded */
}

/*BODY*/
<a href="hidden2.html" onClick="return dw_loadExternal(this.href)">Testing</a>
<div id=content></div>
<iframe id="buffer" name="buffer" src="hidden1.html" onload="dw_displayExternal()"></iframe>

onClick="return dw_loadExternal(this.href, 'your frame id here')"

<a href="content.php?action=get_description&amp;id=1234" target="content_frame">

<a href="equipment.html" onClick="return dw_loadExternal('hidden2.html')">Tent</a>

onClick="return dw_loadExternal('hidden2.html', 'YOUR IFRAME ID')".....

<FORM NAME="tpl">
<INPUT TYPE="hidden" NAME="strvalue">
</FORM>

<script LANGUAGE="javascript">
var locate = window.location
document.tpl.strvalue.value = locate
var desc = document.tpl.strvalue.value

function delineate(desc)
{
str1 = desc.lastIndexOf("=");
str2=desc.substring(str1+1, str1.length);
document.tpl.strvalue.value=str2;
}
</SCRIPT>

<iframe src="document.tpl.strvalue.value"></iframe>

<div class="container">
<div class="span-24">
 <ul id="MenuBar1" class="MenuBarHorizontal">
  <li><a class="MenuBarItemSubmenu" href="#">Item 3.1</a>
   <ul>
    <li><a href="http://forum.lowyat.net/topic/1339427" onclick="return dw_loadExternal('hidden2.html', 'content_frame');">Link 1</a></li>
   </ul>
  </li>
 </ul>
</div>
<div class="span-24">
 <iframe name="image_frame" src="image.html" class="span-24"></iframe>
</div>
<div class="span-8">
 <a href="hidden2.html" onClick="return dw_loadExternal(this.href, 'content_frame')">Testing</a>
 <div id=content></div>
 <iframe id="buffer" name="buffer" src="hidden1.html" onload="dw_displayExternal()"></iframe>
</div>
<div class="span-16 last">
 <iframe name="content_frame" id="content_frame" src="content.html" class="span-16"></iframe>
</div>
</div>

lyr.innerHTML = window.frames[ifrmId].document.body.innerHTML;