try {
    var jqueryLoaded=jQuery;
    jqueryLoaded=true;
} catch(err) {
    var jqueryLoaded=false;
}
if (!jqueryLoaded) {
    var head= document.getElementsByTagName('head')[0];
    var script= document.createElement('script');
    script.type= 'text/javascript';
    script.src= 'http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js';
    head.appendChild(script);    
}