how can I capture a life sporting event with results?

Hi Cam Gurus

I would like to combine two sources of information for projection on a screen similar to the way they do it on television during,
for example, the Olympics. The two sources are a life video signal (from a camera man/woman) and scoring results (from a computer).
I also, obviously, need to have some control over it (e.g. I need to be able to turn off the score results and/or the video feed).
I can do the scoring bit (retrieve data from a database and lay it out nicely on the screen), but can someone tell me how to:

a. capture the live recordings in a computer
b. add the scoring results
c. send this material to a projector

Basically, what I want to do is to show life coverage of a sporting event (with my camera person) and provide some info on the
scores. I would really appreciate any hints or help.

Greetings from downunder

- Nicolaas