The software, loaded with the long name of "Microsoft.Windows.Vista.Local.Activation.Server-MelindaGates" is available on several pirate Web sites. It spoofs a Key Management Service server, one of the two technologies that Microsoft debuted last month that let businesses activate a large number of copies of Windows Vista. KMS requires that at least 25 PCs be connected to a corporation's network.

Vista is the first version of Windows that Microsoft requires volume license customers to activate. Besides KMS, the Redmond, Wash. developer also offers Multiple Activation Key, which resembles the retail version's activation process. PCs activated using KMS must reactivate at least once every six months.