Windows xp is an amazing operating system,it offer flexibility tto user to use the system as will.Check out this amazing trick to create an invisible user account

1. Click Start > Run > then type 'regedit'
2. Search for the following registry key: HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/WindowsNT/CurrentVersion/Winlogon/SpecialAccounts/UserList
3. Create the Value Data Type and Value Name as detailed below. If it already exists, just edit it.
4. Data Type: REG_DWORD [Dword Value]
5. Value Name: Type Name of Account to be Hidden
6. Setting for Value Data: [0 = Account is Hidden / 1 = Enabled]
7. Exit Registry and Reboot

Remember that the account profile will be visible in C: Documents and Settings or wherever user profiles are stored as well as in Local Users and Groups. But, to the average user...To log into this account you should be able to press Ctrl+Alt+Del at the logon screen and then input the user name and password.