$66.8 Million isn't in the neighborhood of $100 million. Yes, they're both huge sums of money, but not close enough to go "meh, close enough." Thanks for the link though - I'm somewhat surprised Mozilla made as much money from a non-Google source as they did.
That $67 million dollar figure was from 2006, and that was up 26% from 2005. I can only assume 2 more years of continued growth and more market share have brought that number up substantially.
I'd bet that Microsoft would pay a lot more than that, but Mozilla wouldn't accept it (at least not for the moment) since Google's is perceived to be the best search engine. So they do the right thing and have Google search being the default.
What happens when Google doesn't need that?