they're not compatible with the V2 tagging that WinAmp uses.
It actually is the other way around!

Helium uses the most current version of the ID3v2 standard, Winamp is using an older version... So the guys developing ID3v2 haven't thought much about backward compatibility? Guess we have to wait for Winamp v3 then .

On the other hand, Helium is 100% compatible with MusicMatch tags!!!! And in a short while Helium2 will appear

Edwin de Vaan
mk2 rev.7 # 080000263 (queue 1232) 6+20Gb blue/red