Of all the sinister things that Internet viruses do, this might be the worst: They can make you an unsuspecting collector of child pornography. Heinous pictures and videos can be deposited on computers by viruses — the malicious programs better known for swiping your credit card numbers. In this twist, it's your reputation that's stolen. Pedophiles can exploit virus-infected PCs to remotely store and view their stash without fear they'll get caught. Pranksters or someone trying to frame you can tap viruses to make it appear that you surf illegal Web sites. Whatever the motivation, you get child porn on...