Here is the trick to make windows user account as hidden.Nobody knows there is account in xp and it is very helpful when you want to store data which is not shown to other users who works on your computer.Just follow below steps to make account invisible.
first go to control panel then to user accounts there create a account and give your desired name after creating account we need to make it invisible so open the registry.
click on start->run->enter regedit and press ok, then it opens the registry. Now go this path in the registry
Now on the right pane right click on any where then select create new dword and give its name as that you given name for user account for example if i created account with name “user” then i give the dword as “user” then give the dword value as 0 which means invisible and where 1 as visible.
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Now close the registry restart your computer then on logon screen your created account is not shown in order to login to that account press ctrl+alt+del key then a window prompts with user name and password, enter your details thus you can make account hidden.