Does anyone understand why a mac should register on the network while 2 PCs don't?

Did you try replacing the network lead with a crossover network lead (or non-crossover lead if you're already using a crossover lead).

The PowerBook is likely to autodetect what sort of cable you've got, whereas the windows boxes may not.

Alternatively the windows boxes are looking for services on the network (that aren't there) to determine if they're on the network. Whereas the PowerBook is looking for something different.

I suggest you tell the Wife and son to get Macs :)

Have fun,
Shay
--
=========================== Shay  Telfer ================================
 Perth, Western Australia   Technomancer  Join Team Sungroper in the
 Opinions for hire              [POQ]     2005 World Solar Challenge
 http://public.xdi.org/=Shay    fnord     <http://sungroper.asn.au/>