if (document.images) {

  image1on = new Image();
  image1on.src = "images/home-on.gif";

  image2on = new Image();
  image2on.src = "images/about-on.gif";

  image3on = new Image();
  image3on.src = "images/faq-on.gif";

  image4on = new Image();
  image4on.src = "images/schedule-on.gif";

  image5on = new Image();
  image5on.src = "images/news-on.gif";

  image6on = new Image();
  image6on.src = "images/contact-on.gif";

  image1off = new Image();
  image1off.src = "images/home-off.gif";

  image2off = new Image();
  image2off.src = "images/about-off.gif";

  image3off = new Image();
  image3off.src = "images/faq-off.gif";

  image4off = new Image();
  image4off.src = "images/schedule-off.gif";

  image5off = new Image();
  image5off.src = "images/news-off.gif";

  image6off = new Image();
  image6off.src = "images/contact-off.gif";

}

function turnOn(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "on.src");
  }
}

function turnOff(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "off.src");
  }
}
function changeImages() {
  if (document.images) {
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = eval(changeImages.arguments[i+1] + ".src");
    }
  }
}