The General MIDI music featured in many classic games can sound underwhelming without a fancy hardware synthesizer like the Roland Sound Canvas. To solve this problem, people have created virtual MIDI devices and software synthesizers (soundfonts) that make MIDI sound much more lifelike. Don Allen's Timbres of Heaven is a very slick example. Last month, we reported that Timbres has a new version out and that it's well worth the effort to set it up. If you still need convincing, check out these fantastic samples that Forums members Goku and wcnut have created.
Privateer: Pleasure Base
Wing Commander 3: Success