Just to let you know, we bought ViaVoice used on eBay for about $68 including the Andrea headset/mic. It sat for a long time until we finished up some other projects, but we finally installed it today. It works great, and I want to thank everyone again for the advice.
We almost gave up for a while, though, because we kept getting an error message, that our microphone was not connected. After going through all the trouble-shooting docs that came with it, we nearly gave up & thought we should have bought it new. Then I went to the Mac help window right on the computer, which of course led me to System Preferences-> Sound-> Input. I moved the highlight from "Built-in microphone" to "USB" and it worked fine.
It's good to remind ourselves and other newbies to check out the Mac help at the top of our computers, which often provides the answers we need.
But then there's TS!!
Thanks again,
Lorraine