To enable or disable the administrator account on the welcome screen of Windows XP, click Start, Run and enter REGEDIT. Then Go to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList (note that there is a space in the Windows NT). Right click in the right pane and select New, DWord value. Give the value the same name as the Username on the Welcome Screen (it must match) for the account you wish to hide or show. Double click the new value and set it to 1 to show the account on the Welcome Screen, or set it to 0 to hide the account