if (document.images) {
preload_image1 = new Image(1,1); 
preload_image2 = new Image(1,1); 
preload_image3 = new Image(1,1); 
preload_image4 = new Image(1,1); 
preload_image1.src="images/genbutton1bh.gif"; 
preload_image2.src="images/genbutton1boh.gif";
preload_image3.src="images/genbutton2hvr.gif";
preload_image4.src="images/genbutton1h.gif"; 
}