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) {
		btn_about_over = newImage("images/btn_home_over.gif");
		btn_charts_over = newImage("images/btn_bioguard_over.gif");
		btn_getsignedup_over = newImage("images/btn_lin_over.gif");
		btn_help_over = newImage("images/btn_liver_over.gif");
		btn_home_over = newImage("images/btn_hepatitis_over.gif");
		btn_listen_over = newImage("images/btn_contact_over.gif");		
		btn_resources_over = newImage("images/btn_media_over.gif");
		btn_order_over = newImage("images/btn_order_over.gif");
		preloadFlag = true;
	}
}

function popWindow(fileName, popupName, height, width) { 
	window.open(fileName, popupName, 'width=' + width + ',height=' + height + ',scrollbars=no,resize=no,toolbar=no');
}