Windows 10 is a free upgrade for all 7 and 8.1 users (update: RT too) Wondering how much Windows 10 will set you back? In most cases, nothing. Microsoft has announced that the new operating system will be a free upgrade in the first year for everyone using Windows 7, Windows 8.1 or Windows Phone 8.1. The company sees Windows as a service rather than a product, Terry Myerson explains. Yes, Microsof