function makeRequest() {
  var httpRequest;

  if (window.XMLHttpRequest) { // Mozilla, Safari, ...
    httpRequest = new XMLHttpRequest();
    if (httpRequest.overrideMimeType) {
      httpRequest.overrideMimeType('text/xml');
      // See note below about this line
    }
  } else if (window.ActiveXObject) { // IE
    try {
      httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
    } catch (e) {
      try {
	httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
      } catch (e) {}
    }
  }

  if (!httpRequest) {
    alert('Giving up :( Cannot create an XMLHTTP instance');
    return false;
  }

  return httpRequest;
}