I have followed this guide http://www.macosxhints.com/article.php?story=20090805215651603 in order to prepare an older white MacBook I am selling to a friend. It enables you to update OS X Leopard and all included applications without creating a user account and retaining the first user welcome screen setup (complete with do-do-do-doo-do video). The only problem is that I cannot disable root user via Directory Utility as the guide instructs, as under Edit, the only option is Enable Root User. Is there a way to do this in terminal or in single-user mode? If I miss out this step and reset the System Administrator (root) user via Rest Password in the Utilities menu of the install disc, I can still log-on as root with the password that I initially set, so something has definitely gone wrong. Any help would be greatly appreciated.