function doAJAX(url, data) {
  var request = false;
  var result = null;
  
  if (window.XMLHttpRequest) {  // for Mozilla-Class Browsers
     request = new XMLHttpRequest();
     if (request.overrideMimeType) {
        request.overrideMimeType("text/plain");
     }
  } else if (window.ActiveXObject) { // for Explorer-Class Browsers
     try {
        request = new ActiveXObject("Msxml2.XMLHTTP");
     } catch (e) {
        try {
           request = new ActiveXObject("Microsoft.XMLHTTP");
        } catch (e) {}
     }
  }
  if (!request) { // if an error occured, just do a plain form submit
     // if AJAX is unsupported, then do nothing
     return null;
  }
  
  request.open("POST", url, false);
  request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
  request.send(data);
  
  if (request.readyState == 4) {
     if (request.status == 200) {
        return request.responseText;
     } else { // if an error occured, just do a plain form submit
        // if AJAX is unsupported, then do nothing
        return null;
     }
  }
  
  return null;
}