You saving right but you cant open your beats you made on your mpc on the computer i wish it were that easy. I mean you can play them but its not goin to play what you played. Your PC will recognize the MIDI Data and play data on your PC that responds to it. And thats the piano riff you hear. You need to record your beats to your PC in order to get them to be .wav, mp3, ect files. Saving it as a .mid file allows you to acess it again on the mpc.
STEREO OUTS to PC LINE IN
You will need a recording program such Audacity, Adobe Audition, Sound Forge, ect...