function preloadMenuBGs() {
  var image_path = '/components/images/';
  image1 = new Image();
  image1.src = image_path+'menu-facility-support-bg-over.gif';
  image2 = new Image();
  image2.src = image_path+'menu-manufacturing-support-bg-over.gif';
  image3 = new Image();
  image3.src = image_path+'menu-building-systems-bg-over.gif';
}

addEvent(window,'load',preloadMenuBGs);