// JavaScript Document
  var aryImages = new Array("images/next.png", "images/next_hover.png", "images/close.png", "images/close_hover.png");

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

  function swap(imgIndex, imgTarget) {
    document[imgTarget].src = aryImages[imgIndex];
  }