The Des Moines Register says the lawsuit against Dymin Systems Inc., of Urbandale, was filed in U.S. District Court in Des Moines last week.
The lawsuit says Redmond, Wash.-based Microsoft had told Dymin in July that it must stop selling the computers, but the company persisted.
Dymin President Scott Breitman (BREHT'-muhn) told the Register that there is confusion about the alleged violations because the Microsoft licensing agreements are so complicated. Breitman says Dymin officials didn't believe Dymin was infringing on copyright rules.
The lawsuit says it's unknown how much money Dymin Systems has made from selling the counterfeit software.