Keith,
It looks nice, hard to see functioanlity when no one else is there. Nice that "Admin" tells who leaves the channel.
Maybe make it also echo *name* has joined the channel...

I would make...

Here is what I suggest:

Create a page called secure.php
add the following code as it is: ONLY change " your_login_page "


<?php
session_start();
if (empty($_SESSION['username'])) ...