I just linked you audacity in my previous message. Click on audacity (it was a link). Audacity is nothing to do with ogg vorbis website. It's just an open source program for editing & converting audio files.
& yes, you need to convert your audio files to .ogg format, because...
a. It is the recommended audio format for Visionaire Studio
b. it is open source & thus requires no licenses to use.
c. most other audio formats require special licenses to use commercially.
Also quick note: Your movie files should be in .mkv (matroska) format for the same reasons that your audio should be .ogg vorbis, plus .mkv has multiple language subtitle support which VS can display.http://audacity.sourceforge.net/