All of my songs are 128 kbps CBR mp3s. All of them.
I use iTunes primarily, since I have an iPod, and like the interface overall as compared to any other media player. I've been on iTunes for a long time (I haven't bought any songs, just as a small point), and before they got the auto-album art finder, I went to amazon and saved jpgs of album art, and then applied them to the album.
Recently, I've been deleting the jpgs in favor of the iTunes store's higher-rez art that you can get by just right clicking on an album/song.
The thing is though, windows media player won't recognize this newly imported album art, as it's applied somehow differently.
I'm going to go out on a limb and say that the album art that I applied myself from my own saved jpgs are saved the the id3 tags? I dunno at all, just a guess.
So, bottom line:
When I added all of my music to the windows media player library, it only recognized album art on the albums that I had applied it to myself, not through the iTunes store widget thing. And, after much trial and error, the only mp3s that won't play in Soldat playlists are the ones that I applied album art to manually in iTunes.
Edit: About half of my songs have album art that I saved from the internet and manually applied, and the other half have album art that I've gotten directly through iTunes.
It's not a major problem, it's just something that I find really odd.