People tend to change their operating system (OS) even less frequently than they change their banks

And that's not surprising. OS install is a big hassle, and potentially an even bigger risk. Better the devil you know, as the old saying goes.

But what if the devil you don't know could blow the old one out of the window? That's the kind of claim Google are making for Google Chrome OS. If they're right, people will be flocking in droves to change their OS.

Let's have a look behind the hype and counter-hype. First, those claims. Google Chrome itself is a web browser, which in its nine months of life has attracted an unremarkable market penetration of less than three per cent. But on the back of that, Google says: "We are announcing a new project that's a natural extension of Google Chrome: the Google Chrome Operating System. It's our attempt to rethink what operating systems should be."

One part of that rethink is that Google Chrome OS will be free. This year-end, Google plans to release the code behind the system and make it open-source. According to Google, its OS will be basically having the Web itself as your operating system, allowing you to store documents, spread sheets or Excel sheets on the Internet.

In many ways, this looks like a logical extension of what's already happening elsewhere, in the "computing cloud". All well and good. But Google is a commercial enterprise, not a charity, and it needs to make money. How can it do that from an open-source OS?

One way round that is the definition of "free". Londoners who commute are used to "free" newspapers, for example. They are free to the users – but not to the advertisers. And that might be the way Google plans to go.

Ads on your operating system could be annoying or distracting. Or they could blend into the background, as the ads tend to do on some email systems. Nevertheless, there would be problems. Would companies sign up to an OS that runs recruitment ads for a competitor, for example? Would Google start to charge a fee to switch off the ads, as some services such as "free" online games sites do?

We don't know what Google has in mind, and they're not saying. Their strategy and tactics may well be dictated by the take-up of Google Chrome OS. But if it does take off, it certainly could be the shape of things to come. Watch this space.