It is free but when you click on the link it takes you to their site and tries to get you to try the trial for the paid for version.
Look carefully and in small type at the bottom of the page theres an option for the free one. Click on that and I think that takes you to another page where you can select either the free one or 2 options for paid ones.
When installing watch out for the bit that wants to change your search engine to the one they have and to install the AVG toolbar, just untick the boxes for them at the appropriate point.