Controlling the bootloader Microsoft keeps rival operating systems off Intel machines through coercive, secret contracts. If the OEM does install a rival OS on a machine, Microsoft increases their licensing fee for Windows and puts the OEM out of business. But Microsoft does not need to keep rival OSes off the desktop, their lock on Office formats is enough to keep users from switching to other systems. This is the sort of behavior that makes Microsoft look bad but doesn't really bring them much benefit either. If Microsoft wants to be "free to innovate", why not OEMs?