Ranj - I have the Tomtom Bluetooth GPS box. Very small and good build quality. Costs around 100 notes.
Rob - you need a GPS reciever mate. You can buy a GPS XDA2 cradle which is compatable OR you can buy a Bluetooth GPS box like mine.
The reason why my downlaod was 4.3gig is due to it having ALL of the road maps for the whole of Europe on the DVD. You only need to install the GB maps however it's useful to have if your travelling abroad. Lastly you will need a SD memory card. I would recommend atleast 256mb as they are very reasonably prices nower days.
btw - Ranj, Rob & Justin - don't worry about d/l'ing 4.3gig's if you need all of the European maps and app as I will gladely post it to you guys.
Speak soon..
Sunny.