It seems that Windows Media Player 11 won't read ID3v2.4 tags, either on windows xp or windows 7. Is there a plugin that will the player to fetch ID3v2.4 data?
Why not just convert the ID3v2.4 tags of your music files to ID3v2.3? I believe that Mp3tag can do this. It's probably a good idea to make a backup of your music first.
The v2.4 format isn't implemented everywhere, while v2.3 tags has maximum compatibility.