Lock your PC in one key press

If you want to lock your computer when you leave your desk, you need to change WinXP's default setting for Fast User Switching. Open the Control Panel and click the User Accounts category. Click the Change The Way Users Log On Or Off listing to display your options. Deselect the checkbox next to Use Fast User Switching and click Apply Options. All you need to do from here is hold down the Windows function key and press L. This locks the computer and displays a logon window that prompts you for a password to unlock things.

However, like most people, you probably installed WinXP without a logon password. If so, this makes the lock function worthless because without a password, all it takes is pressing the ENTER key to unlock your PC. Go back to User Accounts in the Control Panel and click Change An Account. Click whichever account you need to change, then click Create A Password to assign and confirm a password.