Evening,

In the long term I will probably look to upgrade to the Mk4 DVD navigation system if one comes up for sale at a reasonable price, however in the meantime I have a good set-up with my phone mounted on the dash to provide up-to-the-minute Google Maps based Sat Nav.

However, I did wonder if it would be possible to update the splash screen on my Mk3 unit, to the new RANGE ROVER one (below) without doing the upgrade to DVD?

 2002 Range Rover Td6 Vogue

Yes. You can. You need to modify the nav SW using a tool called Navtweak.
http://www.bimmerboard.com/forums/posts/293615 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)