Add Users to the Welcome Screen

Start/Run/Regedit

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList
Create a value for the users you want to list (using the Username), and set the value to 1.

Start/Run/Regedit

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList.
Note:  There is a space between Windows and NT.

Add the username you wish to hide as a DWORD value. Set the value to 0 (zero). 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 Win2K logon, 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.