Talking to yourself is a bit weird, but someone might be searching for the answer to this in the future! So far I've discovered that the MFD works by a combination of your GPS antenna and something called GALA. This is used to make the stereo go louder when the car gets faster and also to let the sat nav know you're on the move and how fast etc. I don't think that is either (a) plugged in or (b) working properly. www.vwnavi.com is a pretty bloody useful site for this sort of thing.
yes the MDF is simpler that it looks, I have a MDF2 in the mk5 I also have a FAQ to write up the Aux Socket to an MP3/Ipod gala is a feature from some mk4's which knows the vehicle speed and adjust accordantly unlike off the shelf unit the MFD knows when the wheels are moving via the ABS pump. this feature allows the unit to keep track of the car when signal is lost (I was still on map after going thought a 8 minute tunnel under a river !)
Right...well I purchased a 'plug'n'play' loom from eBay and plugged it all in today. It comes with a switch so you can turn GALA on/off (if you were using MFD for TV/DVD/PlayStation etc). 20.00 - pull the MFD out - plug everything in - push MFD back in and turn on - works fine. Happy days - hope this helps someone else in the future.