function openPopup(filename, name, width, height, toolbar) {

	x = (640 - width)/2, y = (480 - height)/2;

   	if (screen) {
		y = (screen.availHeight - height)/2;
       	x = (screen.availWidth - width)/2;
   	}

	var page = filename;
	var windowprops = 'height=' + height + ',width=' + width + ',location=no,status=no,scrollbars=yes,menubar=no,toolbar=' + toolbar + ',resizable=yes,left=' + x + ',top=' + y;
	var popup = window.open(page, name, windowprops);

}