You answered your own question. If they are from Itunes, they will never work. Steve Jobs has his tiny little carnie hands in each and every file you get from Itunes, and his grip is strong and will never let go. There are programs that will get the DRM out, but you will lose quality and they take forever.
So, word of advice, DONT buy anything form itunes. I use it to organize my music, but NEVER buy anything from it.