function openPopup (popupUrl) {
		var params = "";	
		var popupHeight = 500;
		var popupWidth = 700;
		params += "width=" + popupWidth;
		params += ",height=" + popupHeight;
		params += ",resizable=yes";
		params += ",scrollbars=yes";
		params += ",menubar=no";
		params += ",toolbar=no";
		params += ",directories=no";
		params += ",location=no";
		params += ",status=no";		
		params += ",top=" + (screen.availHeight / 2 - popupHeight / 2) ;	
		params += ",left=" + (screen.availWidth / 2 - popupWidth / 2) ;	
		window.open(popupUrl,'printPreview',params);
	}