if (document.images) {

   alumni_on = new Image();
   alumni_on.src = "/images/alumni2.jpg";

   alumni_off = new Image();
   alumni_off.src = "/images/alumni.jpg";

   members_on = new Image();
   members_on.src = "/images/members2.jpg";

   members_off = new Image();
   members_off.src = "/images/members.jpg";

   register_on = new Image();
   register_on.src = "/images/register2.jpg";

   register_off = new Image();
   register_off.src = "/images/register.jpg";

   update_on = new Image();
   update_on.src = "/images/update2.jpg";

   update_off = new Image();
   update_off.src = "/images/update.jpg";

}

function turnon(imgname) {
   if (document.images) {
      document[imgname].src = eval(imgname + '_on.src');
   }
}

function turnoff(imgname) {
   if (document.images) {
      document[imgname].src = eval(imgname + '_off.src');
   }
}