Hi Amy ....
I can't answer your question precisely but ...
I've been working together with a (more technical) guy to connect a G5 (Tiger) workstation, a G4 Powerbook (Tiger), XP workstations and Linux Ubuntu workstations together on the same LAN ... and we got it all singing and dancing very nicely. There were no issues apart from some authentication stuff but that was only for convenience; not an essential change. This however was using SME 7beta8.
Sorry, but I can't comment on your 'AFP' message.
Best of luck ... Tom.