What budget do you have and what format do you want?
I use Windows Media Encoder to stream 4 different live radio stations, but that's spiraling out of control after a user whined about not wanting to install windows media player on his mac. (deal with it i say, and install the Windows media player MAC version...I don't like the quicktime player for windows either, but what chioce do I have when watching a .mov file?))
Now the powers that be want simultaneous live encoding and streaming in MP3, Ogg Vorbis, Quicktime, Windows Media, and RealMedia.
The first question is what format would require the LEAST amount of support to YOUR end-users? ie: what player do most have installed already?
Count on ignorance to prevent anyone from installing or uprading any extra software or codecs on their own.