Microsoft has confirmed that copies of Windows 10 would be given away to those who wish to test it. Earlier they announced that Windows 7 and Windows 8.1 users can have free upgrade to Windows 10. This comes after reports of Microsoft giving away Windows 10 copies to pirates. All you need to do is install the latest Windows 10 preview (build 10130) and use Microsoft Account that is registered for the Windows Insider program. After this you will receive the final version of Windows 10 for free. Windows 10 will remain genuine and therefore you can have install of the preview and upgrade to the final version later.
It was confirmed on Twitter by Microsoft's Gabe Aul. "As long as you are running an Insider Preview build and connected with the MSA (Microsoft Account) you used to register, you will receive the Windows 10 final release build and remain activated," says Gabe Aul .
Microsoft will soon require testers to use a Microsoft Account to receive updated builds, and even when Windows 10 is finalized testers can opt-in and keep receiving future test versions in the coming months. So if you're running Windows XP or Windows Vista and you're looking to get a free copy of Windows 10, simply install the preview now and you'll get the final copy free once it's ready on July 29th.