Well, i changed the query a bit. I was wondering why the TZ made a diff, and I said screw it, the server is in EST, that is what I will use. Not gonna make it so it is a day from where the person is located, doesn't relly make sense to me. Anyway, here is my new query.
PHP Code:
// first get the current date
$startdate = mktime(0,0,0,date("m"),date("d"),date("Y"));
$enddate = time();
$todayusers=$DB_site->query("SELECT userid, username, usergroupid, lastactivity, invisible FROM user
WHERE lastactivity BETWEEN $startdate AND $enddate
ORDER BY username");