Terry Myerson, Microsoft’s head of operating systems, made official various elements that have dribbled out in recent months after the company said it was planning a summer launch for the next version of its flagship OS. Windows 10 will be a free upgrade for most machines running versions 7 or 8.1 (enterprise versions aren’t included), while Windows Phone owners will have to wait longer. Anyone considering the upgrade should make sure their PC can handle running the new software smoothly. Testing and reviews will provide the best answer, though Microsoft’s initial specifications signal that any PC cable of running Windows 7 or 8.1 should be able to make the leap. The OS will ship with the digital personal assistant Cortana, a new Web browser called Edge and, perhaps most importantly, the beloved Start menu that had been eliminated in version 8.1. Windows 10 will also include free antimalware protection and continuing security updates. Yes, it will have “Candy Cr...