When I bought Logic Pro I never thought to use the orchestral sounds included, but the more and more I use them they are, well, really freaking good at times. So where do the samples come from? I can't imagine Apple doing it. I've heard people say they bought some from VSL, but I don't know. Are they totally synthetic?
One thing that is great about the strings is that they have minimal vibrato, which comes in extremely handy for those haunting sounds. The staccato woodwinds are great also. Granted, i think the programming doesn't make them easy to use, and I've never been able to play them live but after rendering them and doing some eqing I'm kind of blown away.