In the beginning of the film Amadeus, there's a scene where Salieri (as a boy) is in a small church listening to a boys choir. The music is a movement from Pergolesi's "Stabat Mater" (Quando Corpus Morietur and Amen) performed by the Choristers of Westminster Abbey (Simon Preston). If you like this piece - this is THE recording to have.
http://www.amazon.com/Amadeus-Soundtrack-Recording-Wolfgang-Mozart/dp/B000000XBT