"We are trying to make absolutely clear we are not going to leave any space uncovered to Apple," Ballmer said.

Microsoft has seemed to be falling back in recent years, with its traditional dominance of the PC operating system space first eroded by the rise of Apple's Mac OS and open-source alternatives, then rendered increasingly irrelevant by the movement of consumers from the desktop to mobile. And Microsoft - and indeed all other tech companies - have yet to come up with a true and proven challenger to in the tablet field.

The launch of could just change that, which makes now a good time for Ballmer to declare war on all fronts. Apple will no longer have the tablet space to itself, he hopes.

And, he argued, Microsoft has the resources to not only fight Apple on every front, but to beat it.

"We have our advantages in productivity," he said. "We have our advantages in terms of enterprise management, manageability. We have got our advantages in terms of when you plug into server infrastructure in the enterprise... We feel empowered to innovate everywhere and bring our partners with us."