There are so many ways that adware can get on a home computer.  Downloading files is the main way that these programs worm their way in, but they can also attach through breaches in security, or even in pirated software.  This is why it is important to have a great program like Adsgone Popup Killer on your side.  This program keeps the adware from being a problem, as well as making it easier to use your system.  I am happy with the job it did on my system, and I am confident that it will do the job on yours.