The world leader in software has already vowed to challenge a negative ruling, which could involve a fine of nearly 500 million euros and hard-hitting changes to its flagship its Windows operating system.

Here are the company's various options:

-- Microsoft can appeal the verdict in the European Court of Justice (ECJ). The appeal process would last at least two years although Microsoft could ask for its case to be fast-tracked, which could in theory halve the length of proceedings.

-- In the meantime, Microsoft can request a suspended sentence. It would notably have to prove that the verdict's immediate application would cause "serious and irreparable damage". The ECJ would be expected to rule within a few months. In 2003, the ECJ granted suspended sentences in just four cases out of 39, and in only one in 13 anti-trust cases.

-- Once the ECJ reaches its verdict, Microsoft and the European Commission will both have the possibility of appealing again.

SPACE.WIRE