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 you will be purchasing ANY AT&T services online or in store could you mention that you were referred by me? My Employee Referral ID is eo4489. This would be a great help and it costs you nothing, thank you!