We're live 24/7. Sometimes. Swing on by (now!) and say "hi".
If you're not already an IRC user, here's some reading for you:
For possible clients, it really depends on your OS of choice.
For Unix-like systems, Irssi and BitchX seem to be the most popular, but Pidgin also supports IRC:
For OSX, it would seem everyone likes Colloquy:
For Windows, mIRC is almost ubiquitous:
(but you really should fdisk and install a better OS)