Looks like yours was the same as mine, non factory satnav, you can see where someone has cut out the shelf that held the MID unit.
I fitted a Dynavin ( something 99 ) the newer version is the N6 I think, suposed to be better than the one I had.
Saying that the Bluetooth was by Parrott and the sat nav was IGO 8 which is miles better than OEM.
The hardest part was bracketing, but I reckon just drop it in the slot maybe with a Velcro tape around the edges.
The wiring is included and has one to suit pre and facelift X5's.
I found the radio reception a bit iffy and was thinking of fitting an aftermarket aerial instead of the diversity unit built in to the car.
http://www.dynavin.com/products/n6_e53.php