This volume contains 4 stories, one of which is not animated, at least in the first season of the TV series (assuming there will be more seasons).
Note that I'm only going to use chronological episode ordering as released on the DVDs because that follows the novel releases more closely. In the end, though, I don't think it matters much, as even the novel was written in a haphazard order. I'll talk more about that later.
First story is "Suzumiya Haruhi no Taikutsu" (anime episode 7). It's the baseball episode. There's not much more to say because it's very close to the anime version.
Second story, "Sasa no Ha Rhapsody" is a story of Haruhi's first encounter with Kyon. Note that it's _not_ Kyon's first encoutner with Haruhi, however. Huh, you say? There's more. It also describes Nagato's first encounter with Kyon, which again, is _not_ Kyon's first encounter with Nagato. Confused? Well, we've got a time traveler, so we got to have a story about time travel, right? Remember that line in episode 1 where Haruhi asks Kyon if they met before, a long time ago? Well, this story explains that. It's a shame it wasn't animated. According to the afterword section, Tanigawa-sensei wasn't even thinking that this story would continue past the original story (... no yuuutsu), so the fact that that line was in the first story is a mystery to me. It sure worked out nicely, though.
Third story is "Mysteric (Mysterique?) Sign" (anime episode 8). There's not much more to say about this story, again because it's very close to the anime version.
The last story on this book is "Kotou Shoukougun" (anime episodes 9 and 10). I haven't watched the anime version yet since it's yet to be released on DVD, but from an image I see on wikipedia, it appears that there may be some differences. For example, Kyon's sister apparently tags along in the anime. She isn't so successful in the original version of the story.
