Microsoft said late Monday that it had filed 26 lawsuits against dealers of pirated software in seven states, including one against a previously indicted vendor. The companies are accused of either offering pirated material or installing it on computers the defendants sold, Microsoft said.

The Redmond company says that pirated software puts consumers at risk, and hurts its partners that legally offer Microsoft software. Prosecuting software pirates has become an important part of the company's Genuine Software Initiative, an effort to protect its software assets.

Since Microsoft does not sell much of its software directly, and rather through third-party vendors, piracy affects not only the company's bottom line but also that of its affiliates. Since pirates usually offer software at a cheaper price, legitimate companies lose business.

In a statement, Expert Computers president Tim Klan said legal action is necessary to ensure the viability of Microsoft's partner program, and supported Microsoft's actions. His company is a Microsoft Gold Certified Partner.

"Honest resellers are losing business because of illegal sales," Klan said. "Naturally customers are eager to find the best deal, which sometimes happens to be associated with an inferior, illegal product. This is simply unfair, and makes it very difficult for those of us operating within the law to compete."

In its investigation of these companies, Microsoft used a secret shopper-like program where it bought software and then tested it for authenticity. Additionally, phone calls to its piracy hotline were used in compiling evidence.