function get_xmlHttp() {
  var xmlHttp;
  try {
    // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
  }
  catch (e) {
    // Internet Explorer
    try {
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e) {
      try {
        xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e) {
        return false;
      }
    }
  }
  return xmlHttp;
}

