If you have visitors who want to use your computer, then you can enable the Guest Account. It is an account that is available to any user, but has limited rights so the guest user won't mess up your computer.
1.Go to Start, then Control Panel, and then click User Accounts.
3.Click Turn On the Guest Account.
Now a user without a user account on your computer can log on to the computer at the Welcome screen. This procedure applies to computers in a workgroup setting, not to computers that are part of a domain. You must be an Administrator to activate a Guest account.