Does anyone know how to get free licensed music with album artwork?

i tried to download music using imesh but I cant get the music i want imported into my i-pod because supposively i need to covert it to the acc format. All the music from imesh uses the wma format with protected files and i cant put it in my i-pod. I also tried using limewire but i dont get album artwork.... so can some music genius help me? pleaseee. :DD