if (document.images)
    {
      preload_image_object = new Image();
      // set image url
      image_url = new Array();
      image_url[0] = "design/pic/home-but2.gif";
      image_url[1] = "design/pic/samsung-but2.gif";
      image_url[2] = "design/pic/nokia-but2.gif";
      image_url[3] = "design/pic/sonyerisson-but2.gif";
      image_url[4] = "design/pic/benq-but2.gif"
	  image_url[5] = "design/pic/motorola-but2.gif";
       var i = 0;
       for(i=0; i<=3; i++) 
         preload_image_object.src = image_url[i];
    }