Okay, first off, I am NOT affiliated with the site, but I LOVE the software!
www.renegademinds.com downloads area
get the guitar & drum tutor 2 or newer version.
They come crippled but functional, or for a few bucks more you get Ryan (yeah, it is one guy & he won't spam the heck
out of you so don't worry about registering) to register you for the whole program.
and what does it do?
takes any mp3 or dvd file and slows it without changing pitch. also will loop parts of a song.
so now you can learn those hard bass parts!
Dan