vertical menu ?

I am using this vertical menu and I want to change it so that when I mouseOut of the menu everything closes up. Hope someone can help

<script type="text/javascript">
	<!--
		window.onload=show;
		function show(id) {
		var d = document.getElementById(id);
			for (var i = 1; i<=10; i++) {
				if (document.getElementById('smenu'+i)){
						document.getElementById('smenu'+i).style.display='none';
					}
				}
				if (d) {
					d.style.display='block';	
					document.getElementById('smenu'+i).style.display='hide';				
					}
				}
	//-->
</script>


<dl id="menu">

	<dt onclick="javascript:show('smenu1');"><a href="#">Centrifugal Fans</a></dt>
		<dd id="smenu1">
			<ul>
				<li><a href="#">TLT Technology</a></li>
				<li><a href="#">Design Features</a></li>
				<li><a href="#">Performance Benefits</a></li>
				<li><a href="#">Efficiency Aspects</a></li>
				<li><a href="#">Applications</a></li>
			</ul>
		</dd>
	
		
	<dt onclick="javascript:show('smenu2');"><a href="#">Axial Fans</a></dt>
		<dd id="smenu2">
			<ul>
				<li><a href="#">TLT Technology</a></li>
				<li><a href="#">Design Features</a></li>
				<li><a href="#">Performance Benefits</a></li>
				<li><a href="#">Efficiency Aspects</a></li>
				<li><a href="#">Applications</a></li>
			</ul>
		</dd>	

	<dt onclick="javascript:show('smenu3');"><a href="#">Ash Handling Systems</a></dt>
		<dd id="smenu3">
			<ul>
				<li><a href="#">Types</a></li>
				<li><a href="#">TLT Technology</a></li>								
			</ul>
		</dd>

	<dt onclick="javascript:show('smenu4');"><a href="#">Dampers</a></dt>
		<dd id="smenu4">
			<ul>
				<li><a href="#">Types</a></li>
				<li><a href="#">TLT Technology</a></li>				
			</ul>
		</dd>
</dl>

Code (markup):