Mandatory profiles are roaming profiles that the don't get updated when the user logs off. Even if the user makes changes to their desktop settings while logged on, these changes won't be saved, and they will see the same settings the next time they log on. Windows 98, Windows 2000, and Windows XP clients support the loading of Mandatory profiles.
To change a Windows 2000 or Windows XP profile to be mandatory, open the folder on the Logon server where the profile is stored and change the extension of Ntuser.dat from .dat to .man.
To prevent the user from altering their profile in any fashion, you will also need to ensure the share is configured as read-only and the appropriate integrated file system directory permissions are set.