Microsoft CEO Steve Ballmer takes a question during his keynote address at the Search Marketing Expo in Santa Clara, California March 2, 2010.  In an appearance Tuesday at a search engine conference, Ballmer said Microsoft believes Google Inc. has done a number of things to gain an unfair advantage in the Internet's lucrative search advertising market. [Photo/Agencies]

Microsoft CEO Steve Ballmer takes a question during his keynote address at the Search Marketing Expo in Santa Clara, California March 2, 2010.  In an appearance Tuesday at a search engine conference, Ballmer said Microsoft believes Google Inc. has done a number of things to gain an unfair advantage in the Internet's lucrative search advertising market. [Photo/Agencies]