From Wikipedia:

Atonement: Music from the Motion Picture is the Academy Award and Golden Globe-winning soundtrack from the 2007 film Atonement, composed by Dario Marianelli and performed by French classical pianist Jean-Yves Thibaudet. This was their second collaboration with director Joe Wright, following the soundtrack for his 2005 adaptation of Pride & Prejudice.
http://en.wikipedia.org/wiki/Atonement_%28soundtrack%29