Mudlark, I'd recommend a small handheld cassette. I have one that was not expensive which is made for interviewing. It has a thing where I can slow down the playback speed which is handy when typing words up. Anyway, I recommend it because it is easier to interface a regular cassette than a mini-cassette with your computer or to make dubs, etc.

If you ever do want sheet music created from them, I've got a set up where I can transfew them into my hard drive, or play them on my music keyboard, into a program on my computer which then will "spit out" a printed sheet. It's really kind of neat!:-)