Yeah, take that all you Boromir-bashers!
But what you don't find out unless you read the Appendices is that Aragorn has been defending Gondor all along under an assumed name. Of course that's for book-Aragorn only. I don't get much sense of Aragorn's past in the movie (except for the Arwen thing).
But the exchange between Aragorn and Boromir at Lothlorien hints at Aragorn's past defending Gondor. Nothing is said overtly, but he does say he had been there "long ago" and it's obvious in his face that he's remembering those long years spent there. I fully expect that to be referred to more overtly in TTT or at least in RotK.