You are forgetting all the records that initial sales for Halo 2 and Halo 3 went for. The first 24 hours of the release for Halo 2 saw 2.4 million copies sold. In its first week, Halo 3 grossed $300 million.
As for the fanboys only comment, remember, people were saying that the only ones who were going to see Transformers were the fanboys, and that movie shot down those theories fast. How many girls that have never seen a transformers toy before the movie came out of it going "OMG, I LUV Transformers!"? Just check facebook or myspace if you don't believe me.
And don't give me that "Uhh, only people who play Halo know Halo" BS. Everyone knows Halo. Between the product placement, the commercials, the records, and the fact that everyone has played the game, be it male or female, the game is popular. Yes, Batman has more name recognition with a more diverse crowd, but you cannot deny the cultural identity Master Chief has had on the world.