activateMenu = function(nav) {
 if(document.all && document.getElementById(nav).currentStyle){
  var navroot = document.getElementById(nav);
  var lis = navroot.getElementsByTagName("LI");
  for(i=0; i<lis.length; i++){
   if(lis[i].lastChild.tagName=="UL"){
    lis[i].onmouseover=function(){this.lastChild.style.display="block";}
    lis[i].onmouseout=function(){this.lastChild.style.display="none";}
   }
  }
 }
}
window.onload=function(){
 activateMenu('topmenu');
}