Bramwell is right. The "don't end a sentence with a preposition" rule really belongs to Latin, not English.
In English, it's usually considered better *style* to avoid putting a preposition at the end of a sentence, if possible. (For example, in formal writing, "this is the scene in which the boy appears" is better style than "this is the scene the boy appears in"). In some cases, though, it sounds ridiculous or extremely pretentious to move the preposition to an earlier part of the sentence.
(This is especially true when the preposition is part of a phrasal verb. Consider these sentence: "The man stood up." "The car turned around." "The stain won't come out." There's no way to move these prepositions. They have to go at the end.)