Update:

It's been a couple of weeks since I started this thread and I am pleased to say that I have finally got the sound problem solved and I'm ready to burn the edited computer file to DVD. Here's how I worked around my absence of audio in both Pinnacle Studio 8 and Windows Movie Maker:

I found that audio was no problem when using my wife's computer's firewire port, so, I bought a firewire card for my second computer and, happily, it, too, had no problem with the audio. So, I think the problem with the other computer has to do with the way I have the Microsoft Digital Sound System configured---the other computer which works just has on-board audio, as does my wife's computer.

Now that I'm ready to burn, I'm unsure how to proceed. Please take a look at my post #24, above. I still haven't resolved my question 1) in that post regarding getting the proper file format during the burn phase so that the disk will play in a DVD player attached to a t.v. (Chari, heeeeellllppp!!!!)

EDIT: Also, does it matter if I use DVD-R or DVD+R? Do both work okay?