Here's How:
1.Click on Start and then Control Panel.
2.Click on the User Accounts link.
Note: If you're viewing the Classic View of Control Panel, double-click on the User Accounts icon.
3.In the pick an account to change area of the User Accounts window, click on your Windows XP user name.
4.Choose the Change my password link.
5.In the first text box, enter your existing password.
6.In the next two text boxes, enter the password you would like to start using.
Entering the password twice helps to make sure that you typed your new password correctly.
7.Click the Change Password button to confirm your changes.
8.You can now close the User Accounts window and the Control Panel window.