var aryImages = new Array(2);
  aryImages[00] = "img/main/07.jpg";
  aryImages[01] = "img/main/07.jpg";
  aryImages[02] = "img/main/03.jpg";
  aryImages[03] = "img/main/18.jpg";
  aryImages[04] = "img/main/25.jpg";

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

  function swap(imgIndex) {
    document['imgMain'].src = aryImages[imgIndex];
  }