function FactoryXMLHttpRequest(){
   if(window.XMLHttpRequest){
     return new XMLHttpRequest();
   } 
   else if(window.ActiveXObject){
     var msxmls = new Array(     
      'Msxml2.XMLHTTP.5.0',
      'Msxml2.XMLHTTP.4.0',
      'Msxml2.XMLHTTP.3.0',
      'Msxml2.XMLHTTP',
      'Microsoft.XMLHTTP');

     for(var i=0;i<msxmls.length;i++){
       try{
         return new ActiveXObject(msxmls[i]);
       }catch(e){}     
     }
   
   }
    throw new Error("Could not instantiate XMLHttpRequest");  
  }