You are right. Those are the only 2 updateable components

But before you update the nav check the current version on the top right of the Settings screen:
Mk3 = 3-1/63
Mk4 = 4-1/00 (means 4-1/100)
These are the current versions. If yours is older, an update will be advantageous.
Report back if you have a Mk3 - updates can crash the Mk3 if done incorrectly.

To update nav software:
1. Insert nav Operating System CD into nav drive
2. Follow onscreen instructions -do NOT turn off key!
3. Disc will be ejected when complete
The OS CD is available new from BMW for approx US$10, or can be downloaded from various locations

To update map:
1. Obtain new map disc (buy new or 2nd hand)
2. Insert disc

You may find 2008 maps for sale much cheaper than 2009 maps. Check ebay.