Just in case anyone's looking for decent, CC-licensed orchestral samples, I thought I'd let you know about Sonatina Symphonic Orchestra. It's been around for a while, so I'm not sure if it's already common knowledge, but I've only found out about it fairly recently:

http://sso.mattiaswestlund.net/

Though it can't rival commercial offerings, the quality is very good for free samples. It's SFZ format, so can be used in Linux Sampler, amongst many other things; plus, someone has also kindly converted to SF2:

http://www.newgrounds.com/bbs/topic/1262167

A note of caution if using on *nix: there's an issue whereby the file names don't match up, due to incorrect casing (Windows being case insensitive). To fix this, you can apply the patch from here:

http://wootangent.net/2011/02/sonatina-symphonic-orchestra-a-cc-orchestral-sample-pack/

Another helpful soul has put together MIDNAM and Rosegarden maps:

https://github.com/johnsen/Sonatina-symphonic-orchestra-MIDNAM

I've only just started playing with this and haven't properly tested out the maps yet, but it looks very useful so far, so I thought I'd share the above info.