There are three hundred billion stars in our Galaxy, so 100 million Earth sized planets seems like a rather low estimate and a bit of a letdown.

Previous extrapolations, from astronmers that made the news, estimated that there were between 10 and 250 billion (not million) earth sized planets in our galaxy.

See - http://news.bbc.co.uk/1/hi/sci/tech/2078507.stm
or -http://www.cbsnews.com/stories/2010/01/07/tech/main6069284.shtml