TechRepublic’s sister site ZDNet also recently published a guide for people running early builds of Windows 10 under the Windows Insider Program, detailing how to create ISO files from the OS that can be used for a clean install. When installing Windows 10, users will be able to skip the requirement to enter a product key and Windows 10 will activate automatically online. The installed version of Windows 10, Home or Pro, will be the same as the version they upgraded to. There will be no need to purchase a new copy of Windows 10 provided it is being installed on the same Windows 7 or 8.1 machine that was upgraded to Windows 10. People who have upgraded to Windows 10 will be able to download media that can be used to clean install Windows 10 from USB or DVD. Reinstalling an upgraded version of Windows 10 on the same machine will be possible without having to buy a new copy of Windows, according to Microsoft.

Owners of Windows 7 and 8.1 will be able to upgrade to Windows 10 for free but can they keep using that copy of Windows 10 if they need to reinstall Windows or replace their PC? Here's what you need to know about what will happen to your free version of Windows 10 if you need to reinstall or change your PC. Windows 10: Will you lose your free upgrade if you reinstall?

Windows 8.1 free upgrade