BMW Business - Can it be sensibly upgraded?

[StuB]

For a laugh, I asked the stealer who quoted me 'about £3500'.

I have a 53 plate E60 5 series and want to upgrade the BMW sat nav if possible.

Basic problem is that the maps are out of date, but I don't like the bar style displays and would like a moving map, with Points Of Interest etc., which I love on my Tom Tom. My PDA's not really an option as the car has comfort glass, which I understand will interfere with the GPS signal.

I've seen a couple of ad's on e-bay, but would like to know from someone who may have already upgraded.

Thanks in advance.