Here is a list of my favorite sources for free music scores:

http://www.free-music-scores.com/index.htm   music by hornplayer and arranger Jean-Fran├žois Taillard

http://www.free-scores.com/index_uk.php3  a large selection of free scores

http://www.music-scores.com/   some 300 scores, for members

http://www.mutopiaproject.org/ the Mautopia free music project

http://imslp.org/   the International Music Score Library Project (IMSLP)!

http://www.rowy.net/sheet_music.html  mainly for solo instruments

http://www.classiccat.net/  the free classical catalog

http://www.mfiles.co.uk  a rich music site with music sheets, midi, mp3, and more