You can rip sfx from ZSNES if you capture the SPC file just as the sound file is playing, but that's tedious. I have this other program that I assume can capture the sound.
It's called TotalRecorder. It's free, and you can find it off the Internet somewhere.
Once you download this special program, just get your Mario RPG rom near the point where you're about to do the Frying Pan whack (make it a double-hit). Then, before you resume your game, make it so TotalRecorder will start recording.
TotalRecorder records all sounds and music coming from your computer. So it should work.
Do it quick, because in the unregistered version there's a 40-second recording limit.
Once you've recorded the sound and saved it, you can edit the sound in Sound Recorder or wherever, then you could try compressing it in Sound Recorder by saving it in MPEG-3 Layer format (it will still run in Windows Media Player).
Because I can't seem to download the ROM, it would be appreciated if someone else did. I'll keep helping daFunkster until we both manage to get that sound.
It''s hard to save the world when you''re a penguin in wizard clothing.