function newXMLHttpRequest() {
  var xmlreq = false;
  if (window.XMLHttpRequest) {
    xmlreq = new XMLHttpRequest();
  } 
  else if (window.ActiveXObject) {
    try {
      xmlreq = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e1) {
      try {
        xmlreq = new ActiveXObject("Microsoft.XMLHTTP");
      } 
      catch (e2) 
      {
        xmlreq = false;
      }
    }
  }
  return xmlreq;
}

function getReadyStateHandler(req, responseXmlHandler) {
   return function () {
     if (req.readyState == 4) {
       if (req.status == 200) {
         responseXmlHandler(req.responseXML);
       } 
       else {
         alert("HTTP error "+req.status+": "+req.statusText);
       }
     }
   }
 }