function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		nav_ceramics_over = newImage("img/nav-home-over.gif");
		nav_wire_over = newImage("img/nav-company-over.gif");
		nav_zeiss_over = newImage("img/nav-services-over.gif");
		nav_case_studies_over = newImage("img/nav-case-equipment-over.gif");
		nav_company_over = newImage("img/nav-company-case-studies.gif");
		nav_tour_over = newImage("img/nav-contact-tour.gif");
		nav_contact_over = newImage("img/nav-contact-contact.gif");
		preloadFlag = true;
	}
}