function ajax_xmlhttp()
{
   var http;

   try
   {
      if(window.ActiveXObject)  // Internet Explorer
      {
          try 
          {
             http = new ActiveXObject("MSXML2.XMLHTTP");
          } 
          catch(e1) 
          {
             try 
             {
                http = new ActiveXObject("Microsoft.XMLHTTP");
             } 
             catch(e2) 
             {
                http = false;
             }
          }
      }
      else if(window.XMLHttpRequest)
      {
          http = new XMLHttpRequest();
      }
      else
          http = false;

      if(!http)
        http = false;
   }
   catch(ex)
   {
      http = false;
   }

   return http;
}