Microsoft's appeal of the record €497 million fine imposed on it by EU regulators was comprehensively rejected by Europe's second-highest court Monday.

In a landmark ruling, the European Union's Court of First Instance backed the European Commission's 2004 decision to fine Microsoft and order the software giant to change its Windows operating system to make it more compatible with rival systems.

The 248-page judgment comes after nine years of legal wrangling over Microsoft's near-monopoly of the software market and its ability to muscle rivals out of the market.

The ruling's immediate impact probably is negligible because Microsoft already had paid the $613 million fine and, as ordered years ago, has been selling a version of its Windows software without the Media Player that has been the focus of complaints for about a decade.

Broadly, though, some observers worry about an EU that might be too quick to overregulate free markets, especially with Apple scheduled this week to defend its dominant iTunes online music store from complaints that sound similar to those leveled against Microsoft.

EU regulators also are looking at the way Intel prices its microchips and are mulling the proposed Google acquisition of DoubleClick.

Such concerns of overregulation prompted Assistant U.S. Attorney General Thomas Barnett to warn Monday that the Microsoft ruling, "rather than helping consumers, may have the unfortunate consequence of harming consumers by chilling innovation and discouraging competition."