If you want a bit of background information on film scores these wiki pages are useful.
http://en.wikipedia.org/wiki/Film_score
http://en.wikibooks.org/wiki/Movie_Making_Manual-Music
As film tells an emotional story it is obviously critical that the music suits the emotion of the scene. We plan on using mainly classical / opera music for two reasons - its strong emotional content, and because it is free from copyright. There is also royalty free music on the internet that you can buy at a reasonable price (see full list below).
http://www.royaltyfreemusic.com/hollywood-suspense-1.html
(Play sample #2 'Anxiety full')
We plan on using this music for the opening scene (the woman gliding along the water in her boat as she arrives on the island where the philosopher lives - it is in the evening, with full moon and a thick white mist over the water).
And I am a bit of a fan of 'The Great Caruso' so will use some of his classics no doubt!
http://www.muzic.com/enricocaruso/
We also recently watched a live performance of 'That1Guy'.
http://www.that1guy.com/
He is a former double bass player who invented his own musical instrument that is really remarkable. Effectively it is a mix of string, wind and percussion - he creates great sensual violin with resonant pipes (similar to the didgeridoo). Anyway, he owns the music, and we spoke with him after the performance and he is happy to have some of his music used for our film (we have not discussed money yet!)
http://www.pdinfo.com/link.htm - Public domain music resources.
http://www.stonewashed.net/free-music.html
http://www.soundsnap.com/ - Share free sound effects and loops.
http://www.filmsound.org/ - Learning Space dedicated to the Art of Film Sound Design.
http://www.pacdv.com/sounds/free-music.html
http://www.publicdomain4u.com/ - Public Domain Music.
http://www.archive.org/details/audio - This library contains over a hundred thousand free digital recordings ranging from alternative news programming, to Grateful Dead concerts, to Old Time Radio shows, to book and poetry readings, to original music uploaded by our users. Many of these audios and MP3s are available for free download.
http://www.epinions.com/content_1470734468 - List of famous movies that used classical music film scores. (Who could forget Stanley Kubrick's 'A Clockwork Orange' (1971) using Beethoven's 9th Symphony!)
http://www.musopen.com/ - Musopen is copyright free classical music. We take music that is in the public domain, meaning a work that belongs to the community, and have it recorded by individuals and college/community orchestras throughout the United States and stored online so it can be accessed for free through this website.
http://www.muzic.com/ - The Creative Commons Music Sharing License allows music lovers to freely share and listen to all songs found on the muzic website. If you want to remix or use the songs you find on muzic for any commercial purposes, you must obtain the artist's permission.
http://en.wikipedia.org/wiki/Wikipedia:Sound/list - This is a list of full length copyleft/public domain musical works available on Wikipedia or Wikimedia Commons.
http://www.partnersinrhyme.com/ - Royalty free sound effects and themed sound tracks (very good!).
http://www.partnersinrhyme.com/wmcstore/WMCshop.cgi?action=dbview&id=classical - Collection of 50 classical music tracks.
http://www.partnersinrhyme.com/wmcstore/WMCshop.cgi?action=dbview&id=RM14 - Hollywood film soundtracks by mood.
http://www.musicloops.com/classical/ - Royalty free classical music performed by the Apollo Symphony Orchestra available for preview and immediate download.
http://www.sound-effect.com/ - Search for, preview and download royalty free sound effects for immediate use in your multimedia project. A one-time fee gives you a lifetime license for use in as many of your projects as you need. These are high quality sound effects hand-picked from only the best sound designers.
http://www.uniquetracks.com/pack/Cinema.html - The different volumes in Cinema Pack provide movie-type soundtracks for use with Action-Adventure, Romance, Fantasy, Science-Fiction, Suspense, and Chase scenes. There's plenty of ethereal, ambient, and sensual underscore as well.
http://www.uniquetracks.com/ClassicalSeries.html - Large collection of royalty free classical music.
http://www.uniquetracks.com/cd/RS23.html - Eighteen famous Arias from composers like Puccini, Bizet, Delibes and Rossini.
http://www.royaltyfreemusic.com/hollywood-suspense-1.html - We particularly like track #2 Anxiety.
http://www.royaltyfreemusic.com/Cinematic-Orchestra.html
http://opera.suite101.com/article.cfm/free_opera_scores - Public Domain Opera Scores.
http://www.elitevideo.com/index.asp?PageAction=VIEWPROD&ProdID=562 - 40 CD set of various musical styles for $400.
http://www.freshmusic.com/ - Royalty free music - over 2000 themes of excellent buyout music designed to support your video, film or media presentation in a way that will enhance and transform your project. Styles of music range from corporate to new age to sports and motivational to traditional and classical and everything in between.
http://www.spaceandmotion.com/film-screenplays/philosophy-movies-on-truth-reality.htm