[Start] [Run] [Regedit]
You can hide a user in Windows XP using the registry key: HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsNTCurrentVersion
WinlogonSpecialAccountsUserList
Here, first create a data type of REG_DWORD with the name of the user as the value. Then, set the value for this to 0 to hide the account. Next, exit the registry and reboot the system to test whether your setting change worked.