The subject Windows platforms all handle user profiles in much the same way, but there are differences.
The differences can cause W9x profiles to not be transfered to Windows NT 4.x or Windows 2000, unless W9x is upgraded to Windows 2000.
The following are the major differences for each OS.
Windows 95 and 98
When the user logs on, the profile is download from the home directory, defined in the user's account, as a UNC path. You must pre-create this folder. When the user logs off, the profile is copied back to the server.
Common groups are not supported.
A centrally stored default profile is not supported.
The user.dat, the registry portion of the profile, is not interchangeable with Ntuser.dat.
W9x profiles can be stored on a Netware server.
Windows NT and Windows 2000
Both support local, roaming, and mandatory profiles.
Natively installed Windows 2000 computers uses %systemdrive%\Documents and Settings.
Windows NT 4.x, and upgraded Windows 2000, use %systemroot%\Profiles.
Windows NT 4.x handles duplicate down-level account names by adding a .nnn suffix to the username, where the first duplicate is .000 and each subsequent duplicate adds one.
Windows 2000 handles duplicate down-level account names by appending a suffix of the domain name or computer name. If additional duplicates are created, it then adds the .nnn suffix to the domain name or computer name.