ReaLs, пробуй
$preg = mysql_fetch_assoc(mysql_query("SELECT * FROM `users` ORDER BY `datereg` DESC LIMIT 1"));
echo '<div class="menu">Последний зарегистрированный: <a href="' . $home . '/str/anketa.php?id='. $preg['id'] . '">' . $preg['name'] . '</a></div>';