This is one area of sound reproduction in which the most popular cards, such as Creative Labs' Soundblaster series, have remained fairly constant. Greater changes, though, can be traced in music reproduction through a sound card's MIDI interface. That ping, ping, ping might be a piano. By the same token, if you are lucky enough to have a wavetable sound card, such as later model Soundblasters or cards made by Roland or Yamaha, you know how much difference good instrument sounds make. Thus, when a program needs a piano sound, it plays the notes using the sound already stored on your card.
Different cards can play back more instruments at once for richer, fuller sounding music.
Wavetable sounds are actually derived from recordings of real instruments, and thus give a much more realistic tone and clarity to MIDI music than a card that tries to reproduce the sounds on its own. Some cards are even smart enough to let you replace the existing sound with another one if the original isn't realistic enough for you. MIDI is not as important as it used to be. More and more software applications are smart enough to simply play audio and musical recordings directly off of your program's compact disc or your hard drive, meaning you get realistic sound every time. But MIDI is far from dead, and your older applications can get a real boost by having more realistic musical playback.