I installed Ubuntu on an obsolete laptop. Freeware and I think Linux based. I was surprised at how easy it was to install and it's very user friendly, much like windows. I actually use it for certain financial transaction I would like to feel secure and as a back up. Hindsight, I think I could get by with it as a main computer if a person wanted to break the ties with Microsoft or Apple OS. It's well reviewed and has been around for a long time.