function newImage(arg) {
   if (document.images) {
      rslt = new Image();
      rslt.src = arg;
      return rslt;
   }
}

function changeImages() {
   if (document.images && (preloadFlag == true)) {
      for (var i=0; i<changeImages.arguments.length; i+=2) {
         document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
      }
   }
}

if (document.images) {
  rslt = new Image();
  rslt.src = "images/spacer.gif";
}

var preloadFlag = false;
function initPage() {
   if (document.images) {
      norm = newImage("images/ssn.png");
	  over = newImage("images/sso.png");
	  down = newImage("images/ssd.png");
      preloadFlag = true;
   }
}