function rollover()
{
  if(!document.getElementById || !document.createTextNode) {return;}
  var n=document.getElementById('nav');
  if(!n){return;}
  var lis=n.getElementsByTagName('li');
  for (var i=0;i<lis.length;i++) {
    lis[i].onmouseover=function()
    {
      this.className=this.className?'cur':'over';
    }
    lis[i].onmouseout=function()
    {
      this.className=this.className=='cur'?'cur':'';
    }
  }
}
window.onload=rollover;