[jQuery] Converting this mootools code to jQuery....help?

Hey guys, I'm trying to convert my scripts to jQuery, I wondered if
you guys could help me out with this...
window.addEvent('domready', function Online_User_Updater() {
    ajaxRequest = new Ajax(siteURL+'fetch/online-users', {method: 'get',
update: $('usersOnlineTxt')});
        if(ajaxRequest.request()){
             var interval = setInterval('ajaxRequest.request()',300000);
        }
} );