Thanks for the article. It helped.
My problem was that the PCs could access the Mac, but the Mac could not detect or access the PCs. The article your referred me to was for people who were having the reverse problem, meaning that the Mac could access the PC but the PC could not access the Mac.
Nonetheless, you set me on the right trail. I found another article with advice going in the reverse direction: http://lifehacker.com/software/mac-os-x/ho...-mac-247148.php
It worked. Turned out to be as simple as going to the Go menu in Finder and then going to the Connect To box. I then typed in the address of one PC and Bingo! The Mac found it. I added the address of the second PC and I was done.
Don't know why the Mac couldn't do this all by itself, just as Windows did. I guess this is a case where Windows is more intuitive and easier to use than Leopard.