Live Audio Streaming

Hello All! The project aims to design an application whose sole purpose is to play live audio feed. The audio In will be at admin's end. That is anyone who logs to the site will hear what ever the admin is speaking. Considering a minimum bandwidth of 512kbps I would like the audio streaming to be buffer free. I would also require help on what kind of server should be used for this application as I presume a minimum 1000 users will be listening live audio feed at a given time. Kindly send me links for Experience in similar project, as that will increase the probability of working together. Thanks and Regards Accord