Rivits
you need the correct drivers installed on all the computers which are going to print to he printer. Each PC directly addresses the printer, even if its attached to another machine so each has to have drivers
In a network where all machines have the same operating system its relatively easy to pick up machines over the network and map them, though in XP (for instance) it can take some time for them to appear on the network
However when you get mixed windows versions involved, things become tricky as some combinations of operating system will require you to either install the printer as a LOCAL printer, printing to a newly created local TCP/IP port, while others will insist on you creating a network TCP/IP port. Its completely irrational and non-intuitive
Even worse, some newer printer drivers for Vista or Win7 actually use Apple's Bonjour print networking services - which to all appearances starts making mysterious hidden networks-within-networks to create connections
In a mixed network its always easier if the printer is attached to a Win7 or Vista PC - not an XP one. That way you can usually map the printer across the network. Do it the other way and then you have to start creating the fake TCP/IP ports I mentioned above