Single user not an Admin user: A fix anyone?

[lists3-200402]

>A client of mine has Powerbook that was returned back from an Apple 
>authorized service center but there is now an unusual problem.
>
>The single and only user is not an Admin user but is instead a 
>Standard user. As such, no updates can be done. Root is not enabled 
>as far as I can tell. Is there any command within Terminal or within 
>NetInfo Manager that might enable me to modify this single user to 
>Admin status? or do I have to back up and replace the system? If I 
>have to back up and reinstall, where do I find the Apple Mail 
>database?
>--
>Robert Ameeti

boot from osx cd, set root password, boot from hard drive, 
authenticate using root login, create admin user (or change the one 
non-admin user to an admin user).

don