A European Union court upheld an antitrust ruling from 2004 against Microsoft on Monday, rejecting the software giant's appeal.

The ruling from European Court of First Instance upholds a nearly $700 million fine that the European Commission imposed which accused Microsoft crushing competition by tying in its software products to its Windows operating system to the detriment of consumers.

The Commission had also ordered Microsoft to release proprietary information to allow software rivals to work fully with Windows PCs and servers and also to offer a version of Windows without the Windows Media Player.

Microsoft must now comply fully with its legal obligations to desist from engaging in anti-competitive conduct, said Neelie Kroes, the EU competition commissioner in a statement. The Commission will do its utmost to ensure that Microsoft complies swiftly.

Microsoft said it would first look at the ruling to determine its next move.

It is clearly very important to us that we comply with our obligations under European law, said Brad Smith, Microsoft's general counsel. We will study this decision carefully, and if there are additional steps that we need to take, we will take them.

Microsoft was also ordered to cover the majority of costs of the Commission and rival businesses.