How does a biblical literalist interpret the tale of David and Goliath?

Affable Geek's answer to What does it mean to interpret the Bible literally? mentioned the possibility of non-literalists interpreting the story of David and Goliath as a "tale that grew in the telling." This reminded me of something I read many years ago in a Bible commentary. It mentioned that several odd discrepancies exist in the details surrounding the story of David and Goliath, making it appear as if another story had been clumsily inserted into the middle of the text by some scribe. Unfortunately, the book was borrowed and I no longer have it, and I don't remember all the points that were made, but the one I remember clearly, because it was so blatant, was how David, once he volunteered to fight Goliath as Israel's champion, was introduced to King Saul as if for the first time, even though he had been serving in the King's court as a musician for quite some time prior to this. Of course a literalist must necessarily reject this idea that the story is full of later interpolations. How would one account for the apparent discrepancies in the story of David and Goliath, then?