if (document.images) {
	img1 = new Image();
	img2 = new Image();
	img3 = new Image();
	img4 = new Image();
	img1.src = "/images/buttons/nav_biography-over.gif";
	img2.src = "/images/buttons/nav_contact-over.gif";
	img3.src = "/images/buttons/nav_schedule-over.gif";
	img4.src = "/images/buttons/nav_teaching-over.gif";
}