Navigation = 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", "");
        }
      }
    }
  }
}