A coalition of rivals charged on Friday that Microsoft's new Vista operating system will perpetuate practices found illegal in the European Union nearly three years ago.
The European Commission found in 2004 that Microsoft used its dominance to muscle out RealNetworks and other makers of audio and video streaming software and that it made its desktop Windows deliberately incompatible with rivals' server software.
"Microsoft has clearly chosen to ignore the fundamental principles of the Commission's March 2004 decision," said Simon Awde, chairman of the European Committee for Interoperable Systems (ECIS).
The group of complainants includes IBM, Nokia, Sun Microsystems , Adobe, Corel, Oracle, RealNetworks, Red Hat, Linspire and Opera.
The Commission said it was studying the complaint.
Microsoft's new Vista operating system is due for formal release on Tuesday complete with a news conference and party.
"Vista is the first step of Microsoft's strategy to extend its market dominance to the Internet," the ECIS statement said.
It said Microsoft's XAML markup language was "positioned to replace HTML", the industry standard for publishing documents on the Internet.
Microsoft's own language would be dependent on Windows, and discriminatory against rival systems such as Linux, the group says.
They said a so-called "open XML" platform file format, known as OOXML, is designed to run seamlessly only on the Microsoft Office platform.
"The end result will be the continued absence of any real consumer choice, years of waiting for Microsoft to improve -- or even debug -- its monopoly products and of course high prices," said Thomas Vinje, lawyer for ECIS, in the statement.
Microsoft has challenged the 2004 decision, which included a record fine of nearly 500 million euros ($649.4 million) and orders to change its business practices. It awaits a decision by the EU's Court of First Instance.