Compaq was acquired by HP two years ago and eMachines was acquired by Gateway earlier this year. The original licence ended in 1999; the lawsuit follows the breakdown of licensing talks between HP and Gateway.
Gateway spokesman Bob Sherbin said the claim would be vigorously defended, adding, "The fact is that both companies are in possession of significant patent rights in the area of computer technology." He warned, "It's premature for them not to take this into consideration before proceeding for a lawsuit."
HP created an intellectual property holdings subsidiary last year, Hewlett Packard Development Company, which holds around 21,000 patents.