If you regularly log out of your Windows XP/Vista computer instead of shutting it down, try this handy key combination to quickly switch user accounts or "lock" your computer, depending upon your security settings. Press the Windows key (next to the ALT key on many keyboards) and L at the same time. You'll still be logged on, but you'll be able to switch user accounts. If your account requires a password, your PC will be "locked" until you supply it. When you return to the same account, you'll see the same documents and applications that were open before you pressed Windows-L.