Create a Hidden User Account
By using this registry tweak you will be able to hide your account from the Logon Screen and from Control panel users accounts. This tweak works on Windows NT / 2000 and  XP, I've not tried it on VISTA.

What you need?
1. An user account with password

How to-
1-Create an Account with password
2-Go to Regedit
3-Navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\ CurrentVersion\Winlogon\SpecialAccounts\UserList
4- Create a new DWORD Value under UserList
5-Give it the name to the name of the Account you want to Hide
6-Set the Value Data of this DWORD Value to 0 to hide it  and 1 unhide
7- You need to reboot the system to see the changes to take place

Now after rebooting the system you will not be able to see your account on logon Screen now press Ctrl+Alt+Delete when logon Screen Appear another access dialog will appear type your hidden user name and password and press Enter