A Connecticut man known on the Internet as "illwill" was sentenced to two years in prison Friday for stealing the source code to Microsoft Corp.'s Windows operating software, among the company's most prized products.

William Genovese Jr., 29, of Meriden, Conn., was sentenced by U.S. District Judge William H. Pauley, who called Genovese "a predator who has morphed through various phases of criminal activity in the last few years."

Genovese pleaded guilty in August to charges related to the sale and attempted sale of the source code for Microsoft's Windows 2000 and Windows NT 4.0. The code had previously been obtained by other people and unlawfully distributed over the Internet, prosecutors said.

Source code is the blueprint in which software developers write computer programs. With a software program's source code, someone can replicate the program. Industry experts expressed concern that hackers reviewing the Microsoft software code could discover new ways to attack computers running some versions of Windows.

Prosecutors said in an indictment in February 2004 that Genovese posted a message on his Web site offering the code for sale on the same day that Microsoft learned significant portions of its source code were stolen.

Genovese was arrested when an investigator for an online security company hired by Microsoft and an undercover FBI agent downloaded the stolen source code from his Web site after sending him electronic payments for it.

Microsoft, based in Redmond, Wash., had previously shared parts of its source code with some companies, U.S. agencies, foreign governments and universities under tight restrictions that prevented them from making it publicly available.

A Microsoft spokesman said last year that the company was confident the Windows blueprints weren't stolen from its own computer network.