I was a MD fan for a long time, but I'm an enthusiastic Edirol R09 user now.
Fast and simple transfer to computer, noise free recording with the built in mics, long recording time and choice of quality/time tradeoff have won the day.

The Zoom H2 is cheaper and probably just as good. It wasn't available when I bought the Edirol.

A dictation-style voice recorder can be much cheaper but you need to evaluate for sound quality. With careful placement, good acoustics and possible good external mics you could make a saleable recording with the Zoom or the Edirol, but you could never say that about a voice recorder. It might still be good enough for your purpose; I know someone who uses a tiny voice recorder for tune sessions and it's certainly good enough to learn tunes from.

Anahata