Microsoft has stepped up its legal offensive against software pirates with the filing of 20 lawsuits against resellers allegedly engaged in the distribution of illegal software.

The lawsuits, filed against 20 defendants throughout the US, are against companies that allegedly distributed counterfeit software or software components, or participated in 'hard-disk loading'.

Hard-disk loading involves the installation of unlicensed software on computers that are then sold to unsuspecting customers.

Legal actions were filed against companies in Connecticut, Florida, Georgia, Kansas, New Jersey, New York, Ohio, Oregon and Texas.

"We want to make it clear to people who try to profit illegally," said Microsoft senior attorney Mary Jo Schrade.

"Microsoft is determined to protect its intellectual property, while also helping protect consumers and honest resellers from the deceptive and dangerous practices of counterfeiting and hard-disk loading.

"We devote significant resources to helping ensure the integrity of the software marketplace and will not sit by as consumers are put at risk and honest resellers are hurt."

The Redmond giant also announced the findings from its first large-scale forensic analysis of counterfeit versions of Windows XP acquired in 17 countries around the world, which it claims demonstrates that counterfeit software contains risks for typical users.

The findings suggested that one in three counterfeit disks sold in June 2006 could not be installed on a computer.

The remaining counterfeit disks proved to have risks due to tampered code, which could result in denial-of-service attacks, bypass of password protection and application memory corruption.

Of the 348 disks studied, over two-thirds could not be installed on a computer, while 43 per cent had additional programs, or binary code, that are not part of Windows.

"Counterfeit software is big business worldwide," said Schrade. "As this research highlights, consumers and businesses need to make informed choices when purchasing software or risk the possible consequences of using counterfeit software."

Microsoft stated that the legal actions and results of the pirated software analysis announced today are part of a broader Genuine Software Initiative designed to protect the company's intellectual property.