This Instructable requires that you install two freeware applications. This is a Windows-centric project (sorry to non-Win people). It may be possible to do this Instructable on another O/S. There are some optional applications for printing the MIDI file as sheet music or for editing the MIDI file.
One thing I don't get into is how rip one instrument/voice from an MP3 with more than one. If you know how to do this please post an Instructable. I would love to be able to isolate an instrument or voice from an MP3.
As mentioned above the MP3 can only have one instrument/voice.
The sheet music is often a more complicated version than you expect. You may be able to quantize the MIDI file to make it more readable.
The sheet music only displays a treble or bass clef not both.
(Please report limitations that you discover.)
Step 1: Install software (mostly freeware).
Audacity (v 1.3)
Audacity is a really great open-source software. It is handy if you want to record via your laptop/desktop to MP3. It has a lot of effects.
OR get a Portable version at...
Amazing MIDI (v 1.7 )
This is also very cool software. It takes a single instrument input as WAV file and transcribes/converts the music to MIDI file. This software has not been updated since August 20, 2003.
MIDI Notation (v 2.1.2)
This software takes a MIDI file displays it as sheet music which can be printed.
Anvil Studio (v 2007.12.01)
This software takes a MIDI file and allows the user to edit the music. The basic software is free but you can add on some components for a modest price.
I included the version number for the software that I used. In other words, I got this Instructable to work using these versions. But it is usally better to work with the latest stable version.