The P;atalk room worked on the basis that only one PC could have the mike at any time - an honour system of 'putting up a hand' queued requests for such - all others were able to listen - the text chat worked at all times - there was provision of a camera from each person, but those on dialups found it a bit constricting - with a little fiddling, one could get reasonable sound sufficient to hear each performer, one at a time.

I assume Yahoo or MSN would be no worse.