function createAjaxObj()
{
  var resObj = null;

  try
  {
    resObj = new ActiveXObject("Microsoft.XMLHTTP");
  }
  catch(Error)
  {
    try
    {
      resObj = new ActiveXObject("MSXML2.XMLHTTP");
    }
    catch(Error)
    {
      try
      {
        resObj = new XMLHttpRequest();
      }
      catch(Error)
      {
        // kein AJAX verfügbar
      }
    }
  }

  return resObj;
}