if (document.images)
{
  preload_image_object = new Image();
  image_url = new Array();
  image_url[0] = "images/home-roll-button.jpg";
  image_url[1] = "images/products-roll-button.jpg";
  image_url[2] = "images/links-roll-button.jpg";
  image_url[3] = "images/contact-roll-button.jpg";

   var i = 0;
   for(i=0; i<=3; i++) 
	 preload_image_object.src = image_url[i];
}