Millions of European Internet Explorer (IE) users will have the option to choose an alternative browser from 1 March, Microsoft has announced.
It follows a legal agreement between Microsoft and Europe's Competition Commission in December 2009.
Microsoft committed to letting Windows PC users across Europe install the web browser of their choice, rather than having Microsoft IE as a default.
Figures suggest that over half the world's internet users have IE.
Testing for the update is already underway in the UK, Belgium and France.
The software update choice will arrive automatically for Windows XP, Windows Vista and Windows 7 customers, according to a blog post by Dave Heiner, Microsoft's vice president and deputy general counsel.
The blog also contains screen grabs of the message as it will appear.
"Users who get the choice screen will be free to choose any browser or stick with the browser they have, as they prefer," wrote Mr Heiner.
Google Chrome, Firefox, Safari and Opera are the alternative browsers that people will be offered.
"Millions of people who have never really thought about which browser to use will now be forced to make a choice," said BBC technology correspondent Rory Cellan-Jones on his blog.
"That presents Microsoft's rivals with a unique marketing opportunity."
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