For a good look at the state of the battle over consumers' rights, the EFF has
an easy
guide to iTunes
and other DRM-laden commercial music services.
The big music stores aren't the only option, though. You can assert your
rights by using
Ogg Vorbis
music instead of the restrictive AAC/WMA/RM formats, and buy your music from
companies
like
Magnatune
who aren't out to restrict you.