Parental Controls feature in Leopard helps you monitoring and restricting other user activities on your computer. Accounts under Parental Controls will have account status
Managed. And for your information, administrators who declares themselves as under Parental Controls will automatically lose their rights to be an administrator.
Parental Controls is set under System Preferences ▸ Parental Controls. But before that, you must be an administrator and have at least one account under Parental Controls. Transforming account, either it's normal account or it's administrator account, can be done inside System Preferences ▸ Accounts. What are those features for managed accounts :
Simple Finder is suitable only for inexperience users. For experience users, it will be very boring to use Simple Finder because Simple Finder restricts sidebar and even directory managing.