This is actually a difficult thing to do well. In the past, companies like Starlight Networks built some pretty sophisticated hardware, and designed software protocols to make this possible. A lot has happened since then (that was ten years ago), but setting up a one-to-many live feed requires some engineering.

Unfortunately, even though I was heavily involved in video conferencing twelve years ago (which involved multi-point) and wrote several technical white papers for Santa Cruz Networks several years ago (and you might want to click on that link to get some ideas that might help you), I am no longer current. Perhaps others will be able to tell you what hardware and software you'll need to install. It will certainly require a lot more than simply setting up a camera.

BTW, I assume you know this, but you can purchase cameras that include hardware that makes them self-contained mini-servers. What this means is that you can hook an RJ-45 network cable directly to the camera, and you'll be able to view it on the network. These are generally "webcam" quality, however.

On a different aspect of this topic, if you hook up your camera via Firewire, and if you are using a "real" camera (i.e., your camcorder, as opposed to a 320x240 webcam), you may find that much of the software that you'll want to use won't recognize the connection. Maybe this has changed, but most conferencing and webcam software wouldn't talk to Firewire cameras because of the way Windows is architected. However, if you use USB, the output of your good camera -- if it even supports USB -- will probably not be full quality through the USB connection. If this is true, you can feed the analog output of the camera into a USB encoder or capture card. This lets you use the software you want, while still getting the full resolution of the good camera.