function Inint_AJAX() {
   try { return new ActiveXObject("Msxml2.XMLHTTP");  } catch(e) {} //IE
   try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch(e) {} //IE
   try { return new XMLHttpRequest();          } catch(e) {} //Native Javascript
   alert("XMLHttpRequest not supported");
   return null;
};

function countdownload(id) {
     var req = Inint_AJAX();
     req.onreadystatechange = function () { 
          if (req.readyState==4) {
              // if (req.status==200) {
              //      document.getElementById(src).innerHTML=req.responseText; 
              // } 
          }
     };
     req.open("GET", "counter.php?id="+id); 
     req.setRequestHeader("Content-Type","application/x-www-form-urlencoded; charset=UTF-8"); // set Header
     req.send(null); 
}