function createRequestObject()
{ 
   var req; 

   if(window.XMLHttpRequest)
   { 
      req = new XMLHttpRequest(); 
   }
   else if(window.ActiveXObject)
   { 
      req = new ActiveXObject("Microsoft.XMLHTTP"); 
   }
   else
   { 
      alert('Problem creating the XMLHttpRequest object'); 
   } 

   return req; 

}