Okay, ideally there would be a Mac program to convert MSV to AIFF. I couldn't' seem to find one, but that doesn't mean one doesn't exist. If one doesn't exist, two options:
1) Use
WireTap. It records sound from your computer in real time. You would manually have to record each file, then save it as another in any format you wish.
2) Buy
Virtual PC and install one of the many MSV converter programs for Windows.
3) Do the above for your existing recordings, then buy a new recorder that supports MP3 recording.