When Microsoft rolled out the Windows 8 OS, there was displeasure among users when it took away the start menu. With its tiled interface and foreign features it prompted some to stay with Windows 7 and Xp. When Microsoft rolls out Windows 10 soon, it will be a free upgrade for people that have Windows 7, Windows 8.1, and Windows Phone 8.1.
That is if they act quickly. The time frame is one year from when Windows 10 has the official roll-out. Devices must be connected to the internet and have Windows Update enabled, and with Windows 7 Service Pack 1 or Windows 8.1. Here is a link that you can sign up with for news on the official launch and when users can expect to upgrade to Windows 10.