Every family has at least one novice whose risky computer behavior is asking for trouble. You know who we mean: the P2P addict who can't resist those dodgy downloads; the spouse who clicks on suspicious pop-up ads and updates without a second glance; or the cousin who returns a borrowed laptop brimming with malware.

You've got two options: become a paranoid curmudgeon with motion-sensor alarms rigged to your PC, or establish smart security precautions and educate your family members and friends about exploring the Net safely. We've got four basic steps to set you on the latter path.

Though we wish our methods were foolproof, our guidelines can't guarantee total freedom from malware. Criminal hackers are constantly hatching new plans to get around our best defenses. However, following these steps to mitigate your risk will go a long way toward reducing your whole family's exposure to threats.

Step 1: Create multiple user accounts

Windows' user account controls make it easy to restrict privileges for specific users.

A good first step in preparing your PC for shared use is to create separate user accounts for every individual accessing your Windows machine. It is especially true if there have been problems in the past with a household user who has acted less than knowledgeably online. The advantage of multiple user accounts is that you, the über-administrator, can limit other users' abilities to install programs and make system-wide changes, a move that could prevent your guests from executing tainted programs. To sweeten the deal, each account holder can craft their own visual style, adding a password-protected login to help maintain privacy.

In most versions of Windows, you'll simply click the Start menu, open the Control Panel, and select "User Accounts". For each intended user, click "Add" in the Users tab, enter a name, and then select the user type--either power-user status, which allows administrative rights, or restricted-user status, which does not.

Make sure the "password at login" feature is enabled, so everyone who accesses the computer will be required to provide his or her username and password. The nuisance of compelling returning users to log in after each idle period is easily outweighed by the security benefits of maintaining multiple accounts. Besides you can always adjust your idle-time settings to minimize the frequency of login.