Messenger servers

[Da Rock]

I haven't checked the list for around a week- I'm still catching up! :)

I'm trying to sort out a messenger server for work purposes, and
although I've found a few I'm hoping some input from sysadmins who have
deployed these might help our decision. I've found Gale, Jabberd2,
OpenFire, and SJECS (Sun Java Communication Suite).

Our requirements are for collaboration (multiple users simultaneous
chatting together- with audio/video if possible), realtime audio/video
(with a preference for audio; ergo video can go to the dogs to maintain
audio quality, although a means to adjust this- on the fly if possible-
would be useful), and chat.

Tall order, eh? Ease of admin would be good, but my main concern is
stability and reliability (I'll make up a software solution to
administrate if needs be).

Thanks guys.