A second appeal against the anti-trust settlement between Microsoft and the US government is raising the stakes for the software giant.

West Virginia has followed hot on the heels of Massachusetts which last month appealed against a federal court ruling upholding Microsoft's controversial deal with the government.

It is clear that the costs involved will be painful for the states, but such concerns were not material, according to West Virginia's Attorney General Darrell McGraw.

"No reputable government should plea poverty and allow an adjudicated lawbreaker to retain their ill-gotten gains," he said.

Monopoly power

The appeals, if successful, could revive attempts by Microsoft's opponents to break the firm's dominance of the software market through legal sanctions.

Massachusetts and West Virginia are among the nine US states that refused to go along with a settlement last year which ended a federal government inquiry into alleged market abuse by the software giant.

The nine 'rebel' states argued that the original settlement let Microsoft off too lightly, and went back to court to press for tougher penalties.

Last stand

But US District Judge Colleen Kollar-Kotelly rejected their arguments last month in a ruling which endorsed the original anti-trust deal.

The remaining seven rebel states said on Friday they would not challenge the decision.

Market dominance

The original anti-trust probe came in response to complaints that Microsoft had designed its Windows operating system - used on 80% of the world's personal computers - in such a way that it was difficult to run non-Microsoft products alongside it.

Microsoft was found guilty of anti-competitive behaviour, and, under the terms of the final settlement, was ordered to make technical information available to competitors so that they could design software that would run smoothly with Windows.

But the settlement stopped short of breaking Microsoft up into two separate companies, a measure that many of its opponents had called for.