There are a lot of people out there whose sole purpose in life is to make other people miserable. Viruses are a perfect example of this. Windows is the most common PC operating system, which makes it attractive to virus makers. In fact, you should not use a windows computer on the Internet without up-to-date antivirus software. Apple computers are targeted less often, but Mac users should also run up-to-date virus protection. The thing to remember is that some viruses can destroy your computer. If you compare $30-$40 for antivirus software, to $200 or more to repair a dead computer, it really makes sense to get the software.