How do I record with iMovie and broadcast live at the same time?

I record live through iMovie currently. I have camers through a switcher, which connects DV to the firewire input of my Mac Book. I import it live in iMovie and then edit it there after.

I'd like to also broadcast live on a site like ustream. However, I can't get the video to go to both at once.

Any ideas on how to solve this? Software that can do both? A splitter?

There's another Mac Book here if the firewire could be split somehow. I'd prefer to keep it all on the same computer, but it's possible.

Depending on your situation, you might want to look into the Wirecast software from Telestream. Wirecast lets you stream multiple live video cameras while dynamically mixing in other media such as movie clips, images, audio and text. Features such as Chroma Key (green screen), 3D transitions, built-in titles and up to 35 layers of live compositing allow you to create professional broadcast productions for live or on-demand distribution to services such as Ustream, Livestream and Justin.TV, as well as to a wide range of streaming servers.

Basically, you can produce professional-looking live events with just a camera, an internet connection and a computer.

$450 is a little high. Any other cheaper ideas?

Check out BoinxTV. They have a lighter edition that is cheaper than the "full" version which sells for about the same as Wirecast.