If you log into Itunes, you should be able to upgrade your music to Itunes plus which is the format that was introduced some month back, that one does not carry DRM.
Any old tracks you should be able to upgrade to non DRM for a small fee which will also improve the quality significant. There is a button somewhere in the Itunes store, I think when you log in on the right side of the home page it display the number of songs you are able to upgrade ....
Cheers
JK
BS9000, BS2300, BC2, BL2500, BL3, Bl2, BS1, BV8, BC4, A8