How I Organise my PC for Best Performance, Reliability and Ease of Use - Part 6 of a series of tips on good practices for managing a personal computer. The Windows registry is the most important and critical part of the operating system ERUNT is quick easy to use to backup this registry for all Microsoft Windows from NT3.5 to Windows 7. We install this as a "portable" application to keep things simple and clean. Resoring a registry backup can save having to re-install a broken operating system.