Welcome to the forum,

1: Go to your local BMW Dealer.
2: Buy a 2007 map disc
3: Press eject on the nav computer and remove the 2004 map disc.
4: Insert the new 2007 map disc

or get the map disc from navteq.

http://tinyurl.com/23rkac

or get the disc off eBay.

http://tinyurl.com/2d5bml

or download via torrent (not recomended)

http://tinyurl.com/3yjuh4

You could probably do with an OS update as well, look here

http://tinyurl.com/25w99h

Hope this helps.

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.