When deep-pocketed Microsoft rolled out its online entertainment guide "Twin Cities Sidewalk" in July, many people expected it to eventually rule the local online scene. That hasn't happened. In fact, a disappointed Microsoft is expected to announce big changes to Sidewalk as early as this week as it tries to stop the venture from losing so much money. Apparently, not enough people seem to really need a web site that provides lists and reviews of movies, restaurants, and other leisure time activities.