Many users have recycled an old Mac as a printer server, but it does not necessarily runs Leopard or the latest version of Mac OS X, and subsequently Leopard does not find the shared printers managed by a Mac running Mac OS 10.2 or 10.3.
In a dedicated TechNote, Apple offers a solution to bring shared printers back. You will have to enter the following command line:
cupsctl BrowseProtocols='"cups dnssd"'
You can reinitialize the printing system via right-click (or Ctrl-click) on the field containing all printers in the Preference panel (Printers and Fax)
If it does not work as described by Apple, Macosxhints offers a second solution, rather straight forward with the
