Never install a custom OS on a machine that contains sensitive personal data, banking information, or work files. It is best used on a secondary machine or a Virtual Machine.
A standard Windows install requires hours of tweaking: turning off data collection, uninstalling pre-loaded games, and adjusting privacy settings. A custom ISO like one found on WindowsLite.Net often comes pre-tweaked. The user installs it and immediately has a clean, functional system. WindowsLite.Net - HalloWeen OS.iso