startList = function() 
{
    if (document.all&&document.getElementById) 
    {
        navRoot = document.getElementById("nav");
    
        for (i=0; i< navRoot.childNodes.length; i++) 
        {
            node = navRoot.childNodes[i];
            if (node.nodeName=="LI") 
            {
                node.onmouseover=function() 
                {
                    this.className+=" over";
                }
            
            node.onmouseout=function() 
            {
                this.className=this.className.replace(" over", "");
            }
           }
        }
    }
}

window.onload=startList;