Hide User in Windows XP

Hide the Last User Name
This setting can be used to blank the username box on the logon screen. This will prevent people that are logging on from knowing the last user to access the system.

Windows 2000 or XP
Open [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System] and create a new string value, or modify the existing value, called "DontDisplayLastUserName" and set it to "1" to enable or "0" to disable the restriction.

 

To hide a user's account from the welcome screen in Windows XP:

Open Registry Editor.

In Registry Editor, navigate to the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList

Create the following entry:

Username: REG_DWORD

(Where Username is the username of the user you want to hide from the Welcome Screen).

Assign a value of 0.

Close Registry Editor.

Reboot.

Quote
This will prevent the user from showing up on the welcome screen. You will need to press CTRL-ALT-DEL twice at the logon screen to get the old W2K logon style box to be able to logon to the account you've hidden. Adding a username and setting the value to 1 will cause that user, such as Administrator, to show up on the Welcome screen as well.