Microsoft denied charges in its first trial of a class-action suit  that it abused its operating system monopoly to hike prices.

The trial asks for monetary damages for a total of $425 million if Microsoft were found guilty of using its dominant position in personal computer software to inflate profits.

Microsoft's lawyer argued that in the 1990s, the price of Windows "has stayed about the same while the quality has gone up. In the other two markets, Word and Excel, the prices have actually gone way down."

The Plaintiffs' lead attorney, Richard Hagstrom, said he would prove that "Microsoft's prices are higher than what consumers would have paid in a competitive market."

The seven plaintiffs, representing a class of 1 million homes and businesses in Minnesota, have about seven weeks to present their case, after which it will be Microsoft's turn.

Since last year, Microsoft has reached settlements in nine states and the District of Columbia totaling more than $1.5 billion.