Microsoft has announced it will offer a free version of its popular Office software suite on the internet, challenging rival GoogleÔÇÖs own version, Google Apps. The move has been seen as an attempt by the Redmond, Washington-based company to protect itself from Google, which already dominates the internet search market. The web-based version of Office, which is expected to become available next year, could eat into revenue generated by sales of the traditional version, one of the most lucrative arms of its business.