function createXMLHttpRequest(){
  try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) {}
  try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {}
  try { return new XMLHttpRequest(); } catch(e) {}
  alert("XMLHttpRequest not supported");
  return null;
}


function download(idx){
  var xhReq = createXMLHttpRequest();
  xhReq.open('GET', 'http://www.megamp3.cz/_cat_count_song.php?download='+idx, true);
  xhReq.send(null);
}