This information from pcworld.com contains valuable and informative tips on keeping unwanted programs from being downloaded when you install software from the internet, especially free software.
The sources for free software have become very tricky in disguising what they are installing in addition to their program. I had just read this article today before installing some free software on my son's computer, and was able to avoid installing four unwanted programs with knowledge from this article. Take time to read this article - I can guarantee it will pay off in the future.
Happy ancestor hunting.