sfHover = function() {
   var sfEls = document.getElementById("horiz_nav").getElementsByTagName("td");
   for (var i=0; i<sfEls.length; i++) {
      sfEls[i].onmouseover=function() {
         this.className+=" sfhover";
      }
      sfEls[i].onmouseout=function() {
         this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
      }
   }
}
if (window.attachEvent) window.attachEvent("onload", sfHover);