I think it's a very good idea, too
I am a confirmed technophobe but have been looking for solutions. (You'll notice I was hanging back waiting for somebody with real computer knowledge to point us in the right direction!) I'm hoping I haven't got this too wrong.
i) Doesn't MSN Messenger allow you to have a conversation with multiple others on your contact list? I'm not sure if it'd work well with loads of people at once but, if it's by invite only, I'm guessing it's more secure. You can block people when not chatting, too.
ii) There are a few sites which allow you to create a chatroom, eg
Paltalk, (I used this on a previous computer and found it ok). You don't have to download any software but you do have to sign up/ create an account.
(I'll keep Googling for possible solutions...)