Several people already mentioned Samba/iX :-)
Let me add, in regard to the network neighborhood, that it seems to
be helpful in many cases to configure the Samba/iX server to use WINS
for NetBIOS name resolution (and browsing support?).
If your PC network already uses an existing WINS server, you can tell
Samba in smb.conf to also register with it (see "wins server="). If your
PC network does not use WINS so far, you might tell Samba to act as such
(see "wins support=") and have all your PC's reference it.
Windows NT seems to be less tricky with the NetHood than Windows 95.
Lars "far from being a PC networking expert".
PS: www.samba.org mentions two books on Samba, not specific to MPE/iX,
but nevertheless quite educational regarding the fundamentals of NetBIOS
and PC networking. At least the one that I read was very good.