If you listen to the news, you've probably heard about hackers and viruses. But unless your computer has been targeted by one, you may not know how they could affect you. If your computer is attacked by a hacker or virus, you could lose important personal information or software stored on your hard drive. You also could lose valuable time while you try to repair the damage. Without your knowledge, your computer could even be used to attack other computers, including those that protect our national security.