function preloadImages()
{
   for (i=15;i<20;i++)
   {
      preload_image     = new Image(); 
      preload_image.src = "images/index_on_"+i+".gif";
   }   
   for (i=23;i<27;i++)
   {
      preload_image     = new Image(); 
      preload_image.src = "images/index_on_"+i+".gif";
   }   
   for (i=33;i<48;i++)
   {
      preload_image     = new Image(); 
      preload_image.src = "images/index_on_"+i+".gif";
   }   
   for (i=1;i<5;i++)
   {
      preload_image     = new Image(); 
      preload_image.src = "images/add_to_cart_off_"+i+".gif";
   }   
}
function menuItem(id, status)
{
   document.images["image_"+id].src = "images/index_"+status+"_"+id+".gif";
}
function toCart(id, status)
{
   document.images["cart_"+id].src = "images/add_to_cart_"+status+"_"+id+".gif";
}
function toCheckout(id, status)
{
   document.images["checkout_"+id].src = "images/menu_bottom_"+status+"_"+id+".gif";
}