if (document.images)
    {
      preload_image_object = new Image();
      // set image url
      image_url = new Array();
      image_url[1] = "_images/home/guggenheim.jpg";
      image_url[0] = "_images/home/cata.gif";
      image_url[2] = "_images/home/phillips.gif";
      image_url[3] = "_images/home/gcam.jpg";
      image_url[4] = "_images/home/helm.jpg";
      image_url[5] = "_images/home/sandp.jpg";

       var i = 0;
       for(i=0; i<=5; i++) 
         preload_image_object.src = image_url[i];
    }