The risk of infection will be lower if you only install legal software in your computer.

On the contrary, if the program you are using came in a pirated CD-ROM or is legal software which has been manipulated in order to break the manufacturer's protection, there is no way to be sure whether the product is virus-free.

Moreover, in the case of the antivirus software, the program's legality allows users to enjoy all the additional services that guarantee its efficiency and protection.