Puppy Linux was started 10 years ago by an Australian Electrical Engineer who believed that an operating system does not need to be as complicated as the mainly used Windows. He started with an inherently secure linux base and removed everything that was not applicable for home use. The result was a very fast small system that has no updates or virus checkers. It is designed for personal use and installs in a few minutes with the inbuilt ability for dual booting with Windows. I have personally used it as my main operating system for several years, always booting in under 20 Seconds and never slowing down. The only application that automatically updates is the Browser with the built in E-mail client. Puppy linux is a live CD that can be installed on a Flash drive or a Hard drive.
Windows 10 is going to be a free update for all computers running XP to Win 8.1. What is not being stipulated is how Microsoft is to Monetize this. The most likely outcome will be a yearly subscription. When a computer is updated the original license will be cancelled so there is no turning back. Older programs may not work on the new system so care needs to be taken before updating. The release is scheduled for the middle of 2015.