imageArray = new Array();
  current = "";
  function load_img(name_src)
  {
    if(document.images) {
      var temp = imageArray[name_src];
      if(! temp) {
        temp = new Image();
        temp.src = name_src;
        imageArray[name_src] = temp;
      }

      return temp;
    }
  }
  function replace_img(name, name_src)
  {    
    if(document.images) {
      if(name != current) {
        document[name].src = load_img(name_src).src;
      }
    }
  }

	load_img("images/nav_home_over.gif");
	load_img("images/nav_news_over.gif");
	load_img("images/nav_reading_over.gif");
	load_img("images/nav_programs_over.gif");
	load_img("images/nav_students_over.gif");
	load_img("images/nav_parents_over.gif");
	load_img("images/nav_teachers_over.gif");


	var imagenumber = 7 ;
	var randomnumber = Math.random() ;
	var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ;
	images = new Array
	images[1] = "images/banner_image1.jpg"
	images[2] = "images/banner_image2.jpg"
	images[3] = "images/banner_image3.jpg"
	images[4] = "images/banner_image4.jpg"
	images[5] = "images/banner_image5.jpg"
	images[6] = "images/banner_image6.jpg"
	images[7] = "images/banner_image7.jpg"
	var image = images[rand1]