Consult experts or the Apple website if in doubt.
The hardware requirements are modest: 500 MHz or less suffice; faster machines will yield higher precision in some situations.
Now comes the little qualification: Whoever uses neither a sound card nor an external MIDI device, but works with software substitute, will hardly be happy with MidiCond because of delayed reaction. In particular, most notebook computer owners will profit from an external MIDI module, which may be wired by a USB adapter. The response time of the MIDI device is of paramount importance! In contrast, the sound quality may follow your individual requirements and budget.
What the sheet music is to the conductor, the MIDI file is for MidiCond. Acquire such files for your pieces of music or create them by other software. Fortunately the Standard MIDI File format used by MidiCond is, as the name says, a world-wide standard. Enormous libraries are available in the internet as well as on data media, largely even free of charge, though not all meeting high demands. Feed "MIDI files" to an internet search engine; better still, add a branch of music, for instance "classical MIDI files" or "MIDI files" chanson.
Furthermore, almost every notation program and sequencer can write its scores to such a file (“export”); these programs can likewise be obtained in a large variety of price and quality, starting with free (search under sequencer etc.). Software to produce MIDI files by scanning sheet music is available as well.