Aeolus

Aeolus is a synthesised (i.e. not sampled) pipe organ emulator that should be good enough to make an organist enjoy playing it. It is a software synthesiser optimised for this job, with possibly hundreds of controls for each stop, that enable the user to "voice" his instrument.

Main features of the default instrument: three manuals and one pedal, five different temperaments, variable tuning, MIDI control of course, stereo, surround or Ambisonics output, flexible audio controls including a large church reverb.

Aeolus is not very CPU-hungry, and should run without problems on a e.g. a 1GHz, 256Mb machine.