var aryImages = new Array(2);

  aryImages[0] = "images/info_promo02.jpg";
  aryImages[1] = "images/info_promo01.jpg";

  for (i=0; i < aryImages.length; i++) {
    var preload = new Image();
    preload.src = aryImages[i];
  }

  function do_swap() {
    if(document.getElementById("promo1").src == aryImages[1]){
        //document.getElementById("promo1").src = aryImages[0];
    }else{
        //document.getElementById("promo1").src = aryImages[1];
    }
    
    if(document.getElementById("promo2").src == aryImages[1]){
        //document.getElementById("promo2").src = aryImages[0];
    }else{
        //document.getElementById("promo2").src = aryImages[1];
    }
    setInterval("do_swap()",1000);
  }