bookup = new Image();
  bookup.src = "images/banner/chart.png";
  bookdown = new Image();
  bookdown.src = "images/banner/chartover.png";
  
function bookdemo(id) {
	if (id == null) {
		openCenteredWindow("BookOnlineDemoForm", 470, 700, "bookdemo.aspx");
	}
	else {
		openCenteredWindow("BookOnlineDemoForm", 470, 700, "bookdemo.aspx?id=" + id,"toolbar=0");
	}
}

function bookevent(id)
{
    openCenteredWindow("BookOnlineEventForm", 470, 770, "bookevent.aspx?id="+id);
}