SAN FRANCISCO, March 10 - Ray Ozzie, whose popular Lotus Notes software helped demonstrate the power of office PC networks in the early 1990's, has gone to work for the PC software king, Bill Gates of Microsoft.

Mr. Ozzie's company, Groove Networks, develops software intended to permit simple collaboration by workers using desktop or portable computers, whether they are in the same office or connected via the Internet.

Microsoft said on Thursday that it would acquire Groove and its 200 employees and that Mr. Ozzie would become one of three chief technical officers at Microsoft.

Groove, which is privately held and based in Beverly, Mass., was founded in October 1997 by Mr. Ozzie, who previously was the designer of Lotus Notes. Financial terms were not disclosed. Microsoft was already a major investor, along with Intel Capital, a unit of Intel. In 2001, Groove was valued at about $250 million.

Mr. Ozzie, who began his career developing minicomputer operating systems, was a pioneer at early software companies including Software Arts, the developer of the first software spreadsheet, VisiCalc.

He also helped the Lotus Development Corporation pursue Symphony, a less successful companion to the Lotus 1-2-3 spreadsheet. Later, from a small design company he founded, Iris Associates, Mr. Ozzie led the development of Lotus Notes, a pioneering program intended to permit groups of office workers to share information and tasks easily. Lotus was acquired by I.B.M. in 1995.