if (document.images) 
{
   img1 = new Image();
   img2 = new Image();
   img3 = new Image();
   img4 = new Image();
   img5 = new Image();
   img1.src = "images/banner/banner_top.jpg";
   img2.src = "images/banner/banner_m_l.jpg";
   img3.src = "images/banner/banner_m_c.jpg";
   img4.src = "images/banner/banner_m_r.jpg";
   img5.src = "images/banner/banner_foot.jpg";
}