function openPop(filename, name, width, height) {

	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=no,resizable=yes,left="+x+",top="+y;
	var popup = window.open(page, name, windowprops);

}