function showTour (whichtour) {
 if (document.getElementById) {
  popupx = Math.round((screen.availWidth-1000)/2);
  popupy=Math.round((screen.availHeight-650)/2);
  window.open(whichtour,'launcher','width=1000,height=650,scrollbars=no,left='+popupx+',top='+popupy+',resizable=no')
  return false;
 } else {
  return true;
 }
}