This is the question we get most often around here, in one form or another. Often it comes from someone who is really, really worried (and you can blame the media for the outsized concerns).
So first things first: Don't worry. Now for the answer: Yes. And no.
Yes, an asteroid will hit Earth. In fact ten of them as big as refrigerators streak into the atmosphere every year. Most burn up on the way in, and about two-thirds of the rest (or chunks of them) fall harmlessly into the ocean (because the planet is about two-thirds ocean). Many smaller rocks plunge to the surface routinely (interestingly, about one rock from Mars arrives on Earth each month).
For the rest of the story: http://www.lifeslittlemysteries.com/429-will-an-asteroid-hit-earth-are-we-all-doomed.html