the sad fact is I can only run ICQ2Go and Yahoo on my computer at work. I like Yahoo, but all my friends are on ICQ, so I use it. Trillian is a nice thing - it has some features other messengers don't, but I used to have problems with smilies for example.
As for the chat room, I don't really see a need for it either. When there are several people online, one could PM them to have a more personal conversation... I'm not a fan of chatrooms anyway