So at long last Google is making its move. Promising a lightweight but fast operating system - Chrome OS - the internet search company is poised to strike at the heart of Microsoft's software empire.
The Windows operating system is Microsoft's cash cow, powering about 90% of the world's personal computers, and as a result accounting for the majority of its profits.
The benefits are wider, though. Every Windows desktop comes with an invitation (and at times the imperative) to use other Microsoft software and services.
This, in turn, hobbles Google's ambition of organising all the world's information, and making money on the back of it.