"A first reading of the published order does not affect a later reading of the chronological order." I agree with Wikipedia here. It is better to read the books in the published order first, using an outline of Narnia history to keep the events straight. The second reading may be done in chronological order if the reader desires to experience the creation of Narnia first-- The Magician's Nephew is like Narnia's "genesis", but that is mainly from the Narnian's historical point of view. There is something valuable gained following the stories through the Narnians' time. However, we can also see the perspective of the author's writing more by reading the books in the sequence that the author created them-- especially as we venture into Lewis' ideas.
Larry W.