If you have multiple people using your PC, you should assign each user in your household his or her own password-protected user account. Anyone trying to access another user's account and files without the password will then be denied access.
From the Control Panel, click User Accounts.
Click Create a New Account.
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Different Users
You can create three types of user accounts computer administrator, limited, and guest. You should set yourself up as an administrator because only this account can make systemwide changes to your PC.
When the User Accounts screen appears, enter a name for the account.
Click Next.
On the Pick an Account Type screen, check either the Computer Administrator or Limited option.
Click the Create Account button. Windows XP now creates the new account and randomly assigns a picture that will appear next to the username.
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Change Your Picture
You can change an account picture by returning to the User Accounts utility, selecting the account, and then selecting the Change My Picture option.
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Create a Password
By default, no password is assigned to the new account. You can assign a password by returning to the User Accounts utility, selecting the account, and then selecting the Create a Password option.