I bought the Intel 815EAL with LAN and I cannot play anything that requires MIDI files. There is no install for MIDI but the regular sound works fine. I've tried reinstalling the motherboard drivers but still nothing.
Its also probable that you have a minidriver that does not have midi sound fonts, so in this case you need to download not 3meg but rather 15 meg installation. Also, do you have Creative PCI128 or AD 1885 SoundMax on board?