I read a thread at OXAudio about Synful, a synthisizer plugin with some real promise for realistic orchestral instruments with much lower requierments for CPU and storage compared to sample plugins. It's just for Windows now but an OSX version is in the works.
Here's the Synful site. http://www.synful.com/index.htm
Here's the thread.
http://www.osxaudio.com/forums/viewtopi ... 474#132474
Here's a MP3 of a solo violin.
http://www.mimesc.com/music/SynfulSoloViolin.mp3
I found two more MP3s using Synful. This is definitely break through technology as the violin solos can be quite emotive and the brass quite sharp.
http://www.mimesc.com/music/Andante-Synful.mp3
http://www.mydocsonline.com/pub/fredpro ... 20Demo.mp3