Hi Mabril,
Thanks for trying out Notation Musician.
If you use (in Musician) Setup/MIDI Device Configuration (not the "Quick" one), what device(s) do you see listed there? If the "Microsoft GS Wavetable Synth" is listed there, then (1) right-click it and (2) check the "Set as default playback device" (about half-way down the list.
It won't sound terrific, but you should at least get some sound.
If that doesn't get you sound, then you probably will need to at least update the drivers for your soundcard. Hopefully we can avoid messing with the registry
ttfn,
Sherry