function createXMLHttpRequest() 
{
 var req = null;

   try 
   {
     req = new ActiveXObject("MSXML2.XMLHTTP");
   }  

   catch (err_MSXML2) {

     try
     {
       req = new ActiveXObject("Microsoft.XMLHTTP");
     }

     catch (err_Microsoft) {

       if (typeof XMLHttpRequest != "undefined")
         req = new XMLHttpRequest;
     }
   }
   return req;
}