Making a reservation before it releases will ensure your PC will get the new operating system as soon as possible.
So, this means that as we have previously reported, Windows 10 won't be available for everyone at once on July 29. Later on, everyone else will get the upgrade as well. The company will continue rolling out Windows 10 gradually to everyone else who reserved the copy using the 'Get Windows 10' app and those who bought a new PC.
On July 29, Microsoft will begin rolling out its new operating system starting with machines that are part of the Windows Insider Program.
