function changeImage(targetImg1, newImg1) {
  if (document[targetImg1]) {
    document[targetImg1].src = eval(newImg1 + ".src");
  }
}

// Pre-load graphics
home_on = new Image(); home_on.src = "images/links/home_on.gif";
home_off = new Image(); home_off.src = "images/links/home.gif";
about_us_on = new Image(); about_us_on.src = "images/links/about_us_on.gif";
about_us_off = new Image(); about_us_off.src = "images/links/about_us.gif";
contact_on = new Image(); contact_on.src = "images/links/contact_on.gif";
contact_off = new Image(); contact_off.src = "images/links/contact.gif";
faq_on = new Image(); faq_on.src = "images/links/faq_on.gif";
faq_off = new Image(); faq_off.src = "images/links/faq.gif";
training_method_on = new Image(); training_method_on.src = "images/links/training_method_on.gif";
training_method_off = new Image(); training_method_off.src = "images/links/training_method.gif";
products_on = new Image(); products_on.src = "images/links/products_on.gif";
products_off = new Image(); products_off.src = "images/links/products.gif";
services_on = new Image(); services_on.src = "images/links/services_on.gif";
services_off = new Image(); services_off.src = "images/links/services.gif";