If you do a lot of computer recording, you might be interested in this little gem. The Magnus Choir VSTi is a plugin for your DAW that generates very realistic choirs. I was doing a recording of The Moody Blues' "For My Lady" and wanted the large choir sound from the middle eight. I googled "free choir plugin" and came up with a demo of the Magnus Choir. The demo has a loud tone every 10 seconds, but you can immediately figure out the usefulness of this little plugin. You can buy it as a download online with PayPal and work with it immediately. I love it!
They also have other VST plugins for pianos and orchestras etc. at reasonable prices. I haven't tried those as I have the Edirol Orchestrator.
http://www.syntheway.net/