Considering the amount of adware and other rubbish that is bundled with third-party Windows apps these days, this should be installed on every PC (especially those of older relatives).

Website / Download / Changelog / FAQ

Have you ever felt, while installing software, that the installer tries to push additional unwanted programs at all cost? Ever missed a checkbox, and spent hours afterwards removing adware? Ever opened your browser after an installation, only to find out that you have a new homepage, a new search engine, or even a new browser?

Unchecky aims to keep potentially unwanted programs out of your computer.

^ The video above just has music playing so can be muted.