Microsoft has finally agreed to start complying with a European Commission 2004 anti-monopoly ruling against it.
Microsoft has spent three years appealing against the verdict
The commission said the US firm would now "comply with its obligations".
The software giant was ruled to have shut out rivals from its Windows operating system to gain a larger share of the market for web servers.
It will now give third party program developers access to information that will allow them to make systems interoperable with Windows.
It will also substantially cut the fees it charges for such data.
EU Competition Commissioner Neelie Kroes said she had secured the agreement following a phone call to Microsoft chief executive Steve Ballmer.
Microsoft's move comes a month after it lost its appeal against the Commission's 2004 ruling.
The software giant had taken its appeal all the way to the European Court of First Instance, but it upheld the Commission's judgement that Microsoft had abused its dominant market position.
The court also upheld the Commission's record 497m euros (£343m; $690m) fine against the US company.
"I welcome that Microsoft has finally undertaken concrete steps to ensure full compliance with the 2004 decision," said Ms Kroes.
"It is regrettable that Microsoft has only complied after a considerable delay, two court decisions, and the imposition of daily penalty payments."
The European Commission said Microsoft will now charge a one-time fee of 10,000 euros to firms that want "complete and accurate" technical information on Windows software.
In addition, it will also allow the data to go to open source software developers.
Open source software allows users to read, alter and improve its code - in contrast to proprietary software where a company controls the source code.
Further, Microsoft will cut the price it charges for worldwide licences and patents to less than 7% of previous levels.
"It is a victory day for the consumer... not the Commission," added Ms Kroes.
"The measures that the Commission has insisted upon will benefit computer users by bringing competition and innovation back to the server market."