I am a NoteWorthy Composer user and find it excellent value for money.
The one thing it doesn't do - and neither do any of the other similar programs that I know of - is to generate the guitar chords used in an actual MIDI 'performance' file.
But I finally found a semi reasonable answer. The latest version of Jammer (shareware) has a routine which translates the chords for you from any rhythm track on the MIDI file. It is labelled 'Chord Recognition' and works beautifully, once you've determined where the rhythm track actually resides. There is quite a range of display options, but basically it produces what looks like a spreadsheet with the chord name in the appropriate position in the measure. I have found it really useful when I have been stumped by the structure of (say) an unfamiliar or unpredictable Celtic tune. And for those of us who stray into other musical forms you can always look at the jazz chords in 'Midnight in Vermont'.
I guess it should only be a matter of time before someone publishes a simple media player that displays the guitar chords, karaoke style. I gather that the MIDI data is typically there - it's merely a matter of harvesting it.