Much of the blame for slow PC sales has been directed at Microsoft, as IDC stated Windows 8 failed to provide an increase in PC sales. Windows 8 has its issues, sure; Microsoft's latest OS has been criticized for removing the Start button and its unfamiliar new user interface. But it's not just Windows 8's lackluster release -- Microsoft may be a victim of its own past success. Windows 7, which was released to positive sales and reviews, isn't even four years old. Windows XP, meanwhile, was released more than a decade ago, and yet Intel says there are more than 100 XP systems in North America alone. The point is, customers running previous versions of Windows are satisfied enough and don’t feel the need to upgrade.