hi alan
try using
[global]
security = server
password server = "name_of_windows_password_server"
[share]
public = yes
guest ok = yes
read only = no
it worked for me on Redhat 8 &Samba 2.2.7 and Samba 2.2.8
you can also try setting "directory mask" , "valid users" , "writable" and
"read only" if this doesnt do it
tsvi