In only a few steps, you can be fragging like a pro on the tig Q3 server:
Download a copy of Q3 from your favourite source for these things.
Get OSP installed http://www.ausgamers.com/files/details/html/5464
, it's the competition mod for Quake3, comes with a ton of useful features.
Get the threewave mappack, download here http://www.whodah.com/Quake/Files/threewave_16_full.zip
, 35+ high quality CTF maps.
Then install this mappack I made with all the rest, http://www.theirishguard.com/Files/q3/q3tigmappack.zip
, (extract to your Quake 3 directory).
All you need to do then is connect to the tig server, 126.96.36.199, (bring down the Q3 console by hitting the key beneath the ESC key, yea the one with the ? on it, and type /connect 188.8.131.52 ).