After doing some more research, with some prodding by Randy, I found this bulletin: http://docs.info.apple.com/article.html?artnum=306984 which contains a Terminal command that enables Leopard to see printers under Mac OS 10.3 (and others). I followed the procedure and the printers on my 10.3.9 print server are now visible on the Leopard machine. Summary: Out of the box, Leopard will only see printers on networked Macs running 10.4 and 10.5. (And of course it will see other printers as well.) By following the procedure in article 306874, Leopard will find and add printers on Macs running earlier versions. Count: One down, one remaining (the missing "domain guessing.)