So, now that Windows 7 is dead, you may finally consider installing Windows 10.
Contrary to some rumors, the upgrade from Windows 7 to Windows 10 is still free. Thank, Microsoft.
All you have to do is download this, and run in.
Choose “Upgrade this PC now” when prompted.
And wait for a (long) while.
After that, you can enjoy a completely legal and free version of Window 10. Assuming you upgraded an original version of Windows 7, of course.