Microsoft announced it would start offering a browser ballot screen to some European users this week and plans to begin pushing the ballot to all Windows users in Europe the week of 1 March.

The ballot screen, which will be provided via Windows Update, was mandated by an agreement Microsoft reached last year with antitrust regulators in the European Commission. After Norwegian browser maker Opera Software complained to the commission, officials there accused Microsoft of using its OS market dominance to shield Internet Explorer (IE) from real competition.

To seal the deal, Microsoft agreed to provide a screen to European Windows users running IE that displays the top five browsers - IE, Firefox, Chrome, Opera and Safari - and asks customers to choose which to install as their default.

According to last year's agreement, Microsoft had to offer the ballot no later than 17 March and wrap up the updating process by mid-May.

Microsoft will beat that deadline by several weeks, said Dave Heiner, deputy general counsel for the company. "We plan to begin a phased roll-out of the update across Europe the week of 1 March " he said.

Users who live in Belgium, France and the UK can manually download the ballot from Windows Update beginning sometime next week, Heiner added.

Windows XP users will receive the screen as a "High Priority" non-security update, while Vista and Windows 7 users will see it pitched as an "Important" update. In all cases, the ballot screen will automatically be downloaded and installed on PCs that have opted for automatic updates through Windows Update. Users who have set Windows Update differently can decline the update if they wish.

Microsoft originally fought the ballot idea, going so far at one point last year to say it would ship Windows 7, then still in development, to European customers without a browser . Only in August 2009 did Microsoft abandon that idea after it said computer makers and corporate customers griped about the move.

Although IE is not scrubbed from the system if a user chooses a rival browser from the randomly-presented list, Windows 7 users can throw a "kill switch" to disable Microsoft's browser. Windows Vista and Windows XP users, however, do not have that choice.

According to Irish web metrics company StatCounter, IE currently controls 45.5% of the European browser market, while Firefox, Chrome and Opera account for 39.2%, 6.3% and 4.3%, respectively.