Jacques Mattheij, who posted a guest post here earlier this week, has been working, for a while now, on an in-depth article on how to sell your company.
This is the kind of situation one rarely finds oneself in, but when it does happen, it's worth playing the game in full knowledge of the tricks of the trade (and inexperienced founders are often playing against people who have a lot of mileage at managing company acquisitions). If you're in that position, you'll want to read this guide before making any moves that could cost you.