I have an Olympus MD-1150 musical keyboard (meaning a piano keyboard, not a QWERTY keyboard). I am able to hook the keyboard up to my computer using a MIDI-to-USB cable. The keyboard has a MIDI in and MIDI out plug, while the computer uses the USB end. I am able to connect the keyboard to the computer and the connection works, but am I able to also send MIDI files directly from the computer so I can save them on the keyboard? I was told that the computer would specifically need a MIDI out plug for this, not just a USB. Is this true? I hope this makes sense. And I do have the keyboard's users manual, but unfortunately it is less than helpful.
The only sound cards i know that have midi ports are the Soundblasters made by creative. I had one in 1992 for windows 98 but never really learned to use it. However, if you keyboard has a slot for a memory card (Usually SD) you can transfer the file to the memory card and then stick it in the slot and it should work from there.