Europe's Court of First Instance on Monday said the European Commission's antitrust claims against Microsoft are valid and that the software maker "abused its dominant position" while marketing Windows products.

As a result, Microsoft remains liable for the nearly $1 billion in fines that the Commission imposed on it.

"The Court finds that the Commission did not err in assessing the gravity and duration of the infringement and did not err in setting the amount of the fine," said an official statement released by the Court.

Microsoft can appeal the decision, on points of law only, to the Court of Justice of the European Communities. It must do so within two months.

The decision was handed down Monday morning in the European Court of Justice building in Luxembourg before a throng of EU officials, Microsoft representatives and journalists. The outcome of the case was widely seen as a test of the extent to which Europe's tough anti-competition rules can be used to slow a hi-tech juggernaut like Microsoft.

In this case, Europe's regulators prevailed. Microsoft officials were not immediately available for comment.

The European Union fined Microsoft $613 million in 2004 following a five year antitrust investigation sparked by a complaint from Sun Microsystems. The EU cited anticompetitive behavior that included Microsoft's bundling of Windows Media Player with the Windows operating system and overcharging rivals for technical documentation needed to make their software interoperate with Microsoft's Windows server products.

The EU added $357 million to the fine last year after claiming the software maker had not sufficiently modified its behavior.

Microsoft's appeal of the action was not a total loss. The Court of First Instance annulled a portion of the Commission's action against the company that required Microsoft to submit documents, premises and employees to inspection by a monitoring trustee.

Monday' decision, for now at least, puts a cap on bickering between the EU and Microsoft that's been ongoing since the 2004 decision.

As recently as March, the EU accused Microsoft of failing to live up to the terms of the agreement. The European Commission says Microsoft's share of the workgroup server market in Europe has grown from 35% to 75% during the eight years since it has been investigating the company.