The latest list is located at
http://www.mirc.co.uk/servers.ini 
If using Firefox, simply go to File > Save Page As and save it as 'servers', filetype '.ini' and save it to your mIRC directory. mIRC will update its server list straight away. You can always edit the servers.ini yourself and a serverlist for Undernet can be found at
http://www.undernet.org/servers.phpRegards,
