function ajax_request(url, handler) {
  if (window.XMLHttpRequest) {
    req = new XMLHttpRequest();
    req.onreadystatechange = handler;
    req.open("GET", url, true);
    req.send(null);
  } else if (window.ActiveXObject) {
    req = new ActiveXObject("Microsoft.XMLHTTP");
    if (req) {
      req.onreadystatechange = handleAJAXResponse;
      req.open("GET", url, true);
      req.send();
    }
  } else {
    alert ("uh, couldn't get an XMLHttpRequest");
  }
}