For the last few decades, Microsoft would sit down and build a new version of Windows every three years or so. This new version would start shipping on new PCs, but by and large, consumers didn't run out and buy the new version to upgrade their computers. They simply got the new Windows when they got a new computer. With Windows 10, Microsoft isn't even getting cash from those who do want to buy the latest and greatest version. Following the furor over Windows 8 and it's tablet-centric design, Microsoft has announced Windows 10 will be a free update for one year from release.

Update has thus far been a hub for security patches and bug fixes, which is a necessary evil when you're running the most popular desktop operating system in the world. Windows 10 would get "real" updates that add functionality and change the way the OS works over time.