I believe it was '09 or maybe '10 that you could play DVD's on the navigation screen. With coding you could do it while driving (not encouraged) where the '08's you need a module installed behind the radio which requires splicing wires.
It really depends on your preference so get what you feel comfortable getting. This is all that matters.
If any of you are purchasing ANY AT&T services could you mention that you were referred by me? My referral ID is eo4489. This would be a great help, thank you!