of course, we're assuming this has nothing to do with the fact that its easier to distribute these files as mp3s. piracy is wrong.
but yes, itunes will do it for you. if theyre protected AACs, however, you have a few options- burn to CD and re-rip, or find some software on versiontracker or google to strip out the DRM, then convert to mp3 (I dont condone this; circumventing DRM technology is technically illegal).