To hide a user's account from the welcome screen in Windows XP:
1.Open Registry Editor.
2.In Registry Editor, navigate to the following registry key:
3.Create the following entry:
(Where Username is the username of the user you want to hide from the Welcome Screen).
4.Assign a value of 0.
5.Close Registry Editor.
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