Microsoft Knowledge Base Article 305709 contains the following summary:

This article describes how to create a custom default user profile in Windows 2000. A custom default user profile is helpful if several people use the same computer but each user wants a separate profile along with access to shared resources. When multiple users log on locally to the same computer, Windows 2000 uses the built-in default user profile as a template to assign a profile to each new user. You can replace this built-in profile with a custom default user profile so that each new user receives a custom version of the profile.

Because this change is permanent, it is a good idea to make a backup copy of the default user profile, in case you ever want to use it again. The default user profile is in the Default User folder under Documents and Settings.