I would consider the adapter as a last ditch solution, because it will stick out the smartmedia slot and be a prime canditate for knocking and breaking.

You should still be able to get a 128 meg 3.3 v card (I think all the ones still out there are 3.3v devices), stick it in the slot and forget about it! If really stuck get a smaller one; unless you are a midi-file fanatic you aren't going to run out of space even on a 16 meg card.

After that use a PC USB connection and "Musicsoft Downloader" (which is on the driver CD) to move files to / from the PC and keyboard.

Or just get a USB drive - FORMAT IT USING THE PSR3000 - and use that for transfer instead.