This thread is right up my alley, I just wished that I saw it in my email letting me know that it was here.
However, you can do this. Let me tell you what I did in my stake to make webcasting much easier for everyone.
I am using the Clerk computers as the receivers for webcasting. I then take the VGA out and as aclawson said, to a VGA to RGA converter. I then take the audio out of the computer. I then connect them to a RCA balun like this
http://www.mcmelectronics.com/product/M ... 0-/50-7730.
I then ran a cat 5e cable from the clerk's office to the satellite cabinet. At the other end was another balun. I then had our satellite install a switch which would allow me to have the satellite and computer to be piped into the satellite system and into the modulator for the closed circuit TV system. This way we didn't have to have personal laptops, the crab or anything else like that and we can set up TV's in any part of the building that had a coax drop.
We used this set up for the last stake conference and it worked well, except that I had to remove everyone from wireless to maintain good performance. For our next stake conference we are looking to improve the stake center (source) so that it will be a better broadcast.
The above work takes time, but I look at it this way. It is now finished and I will be able to train anyone to do it and not have to worry about other items.
Hope this helps and if you want to discuss more, please let me know.