[Samba] Administrator is root - I don't like it

[Steve A]

The "Samba-3 by Example" instructs you to make a mapping, "root = 
Administrator".  Is this absolutely necessary?  What if someone hacks a 
Windows machine and is able to supply Administrator credentials to Samba?

Is there a way around this?  I can live with having to supply root 
credentials in Windows when joining a Samba domain (but if there were 
another way I would love to know how!), but I wouldn't want any network 
admin to be able to screw with root's account.

Many thanks,
Steve : )