I've always had to use
smbpasswd -a unixusername
then give them a password for smb use... the catch-22 is that SMB uses a completely different password hash algorithm than Unix/Linux /etc/passwd(shadow) passwords, so you can't use the one for the other.
Its much much easier if you use a central authentication database like LDAP (or if its already in use at the site, Active Directory).
Thanks guys, That's what I guess I didn't know. I was going to use AD integration but these PC's are dom members but they logon locally as they run some lame software won't run as a service and needs local admin to work, so I didn't want a domain username sitting accessible.
jlc