NEED Advice for simple webcast solution.

Maybe my doubt is too basic, but i cannot find the best solution. This is the think.

I need to do a really basic webcast: hd camera + projector output (the computer output that has PowerPoint or what the speaker is showing on the projector)

By now i'm thinking on:

sony ex3 - hdsi
>>> so i'll need an hdsi + xga input and all this to my computer

macbook pro with wirecast... maybe another?

i'll really appreciate any advice or better setting for this type of webcast

thank you very much
Paula