if (document.images) {
  image1on = new Image();
  image1on.src = "images/aboutus_rollover.gif";

  image2on = new Image();
  image2on.src = "images/performances_rollover.gif";

  image3on = new Image();
  image3on.src = "images/store_rollover.gif";

  image1off = new Image();
  image1off.src = "images/aboutus.gif";

  image2off = new Image();
  image2off.src = "images/performances.gif";

  image3off = new Image();
  image3off.src = "images/store.gif";

}