Upgrading to the 128mb wouldnt be a bad idea. But u dont have to upgrade in order to get your beats posted. Now IF u do upgrade to the 128mb then u can RESAMPLE your beat, turn it into a wav file, and then export it from your MPC via USB, CD Burner, or your CF card reader.
But lets focus on what u have now. What you want to do is take the OUTS on your MPC and run that to the IN on your PC or Trackrecorder(whichever u use/have).
Now as far as MIDI goes u will need to get that involved if u want to sync your software together wit your MPC so when u press play on your DAW it starts the MPC. Thats another story though and most do that for tracking purposes. Do you want to do indiviual tracking or just send one big Stereo file over to your computer?
Now after all the work has been done(recording beats to PC) then in the software u use Make sure you do the following(at least this is how I do it). -Save the beat within the software(save the project) -Export the beat out as a .wav file -Export the beat out as a mp3 file
You want to have a .wav file of your beat cause that is going to offer better quality along wit not compressing the track to much to were it sounds like garbage.