It's seems downloading valadoc.org is like downloading a CD image :D. So lets do something fun...
This is not about how to use fancy converter like mediacoder. I'll show "the hardway" to convert all of your MP3s to Ogg Vorbis using open source tools only.
I'll assume you have a quick access to command prompt from explorer. If you don't have it, try googling "Command Prompt Shell Extension" and install it.
1. download the CLI (Command Line Interface) tools
here. Inside the zipped file, you'll find:
lame.exe -> Mp3 encoder version 3.98.4 (with mpg123 decoder builtin)
venc.exe ->AoTuV(Aoyumi Tuned Vorbis) encoder 2.2.2
oggd.exe -> ogg vorbis decoder 1.0.1
vorbisgain.exe -> vorbis replaygain version 0.34
tag.exe -> universal audio tag writer version 2.0.52
m2v.bat -> recursive mp3 to vorbis batch command
v2m.bat -> recursive vorbis to mp3 batch command