if (document.images)
{
  preload_image_object = new Image();
  // set image url
  image_url = new Array();
  image_url[0] = "../images/bg_first.jpg";
  image_url[1] = "../images/bg_firstOver.jpg";
  image_url[2] = "../images/bg_second.jpg";
  image_url[3] = "../images/bg_secondOver.jpg";
  image_url[4] = "../images/bg_third.jpg";
  image_url[5] = "../images/bg_thirdOver.jpg";
  image_url[6] = "../images/bg_fourth.jpg";
  image_url[7] = "../images/bg_fourthOver.jpg";
  image_url[8] = "../images/but_1over.gif";
  image_url[9] = "../images/but_2over.gif";
  image_url[10] = "../images/but_3over.gif";
  image_url[11] = "../images/but_4over.gif";

   var i = 0;
   for(i=0; i<=11; i++) 
	 preload_image_object.src = image_url[i];
}