There's thousands of free, downloadable sound samples specially recorded by Philharmonia Orchestra players (currently resident at London's Southbank Center). These samples are suitable for creating any kind of music, no matter what style.
Using the drop-down menu available at philharmonia.co.uk/explore/make_music, you can select from the list of instruments to access an extensive archive of samples which are free to use in almost any way you wish. See full license details below.
License: You are free to use these samples as you wish, including releasing them as part of a commercial work. The only restriction is they must not be sold or made available 'as is' (i.e., as samples or as a sampler instrument).
[Via: Ali Ahmet]