function montaXMLHTTP() {
   var httprequest = false;      
   if (window.XMLHttpRequest) { // Mozilla, Safari,...
      httprequest = new XMLHttpRequest();
   } else if (window.ActiveXObject) { // IE
      try {
         httprequest = new ActiveXObject("Msxml2.XMLHTTP");
      } catch (e) {
         try {
            httprequest = new ActiveXObject("Microsoft.XMLHTTP");
         } catch (e) {}
      }
   }
   return (httprequest);
}