I echo the possibilities with of AUDACITY. My other music hobby is singing acapella in 2 quartets. I use audacity all the time to take a song and slow it down without changing pitch or focusing on a small segment of an mp3. You can slow a song maintaining pitch and try to reverse engineer what you are hearing. I haven't done lots of reccording but I know many quartet guys who do. Some sing separate multiple parts on separate channels and export as a single mix in an mp3 format. I could easily see doing that with guitar too. Best of all Audacity is FREE.

http://audacity.sourceforge.net/download/

TB