If you want to set up a basic computer to run little more than a web browser, perhaps to repurpose an old slow machine, perhaps you need an operating system called ReactOS. It looks and feels like Windows, but it’s free and open source. It’s not a version of Linux with some added skins and themes to make it look like Windows, though. This is a ground-up, from-scratch project to build a completely new OS which is basically a clone of Windows. So you instantly know your way around.