var nowDate = new Date();
var beginDate = new Date("Tue Oct 14 2008 00:00:01");
var endDate = new Date("Mon Dec 01 2008 00:00:01");

if(nowDate >= beginDate && nowDate < endDate){
	window.open('popup.htm', '','status=no,menubar=no,location=no,directories=no,toolbar=no,scrollbars=yes,resizable=no,Width=480,Height=300');
}