samba3 /me not happy :/

[Igaduma]

Hello all,

I have a working samba2.2.8a serving various XP clients.
Important parts of the smb.conf file:
workgroup = RADIOPLANNING
netbios name = BACKBASE
netbios aliases = BACKBASE
server string = Server RadioPlanning
security = SERVER
encrypt passwords = Yes
min passwd length = 0
password server = 172.31.11.150
password level = 1
username level = 1
[RadioPlanning]
path = /d
valid users = <loads of users here>
read only = No

Each time I add a user to samba I create the user on the unix machine with no password set, bogus shell & a distant directory, then I use smbadduser to add the user to samba, for the password I just use nothing.
Add that user to the valid list and off it goes.
This works fine in 2.2.8a and XP but I can't seem to get it to work in samba3, no more smbadduser binary to start, and it seems to be needing a real pdc whereas previously only a workstation did the challenge which was/is good enough for us.

Is there any simple explanation how to setup samba3 in the same way as I did with 2.2.8a?

Thanks for any help,
L