function createXMLHTTP()
 {
  var ajax;
  try
  {
   ajax = new ActiveXObject("Microsoft.XMLHTTP");
  }
  catch(e)
  {
   try
   {
    ajax = new ActiveXObject("Msxml2.XMLHTTP");
    alert(ajax);
   }
   catch(ex)
   {
    try
    {
     ajax = new XMLHttpRequest();
    }
    catch(exc)
    {
      alert("Esse browser não tem recursos para uso do Ajax");
      ajax = null;
    }
   }
   return ajax;
  }
 
 
     var arrSignatures = ["MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0",
           "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP",
           "Microsoft.XMLHTTP"];
     for (var i=0; i < arrSignatures.length; i++)
     {
    try
    {
     var oRequest = new ActiveXObject(arrSignatures[i]);
     return oRequest;
    }
    catch (oError)
    {
       }
     }
 
      throw new Error("MSXML is not installed on your system.");
 }