I fancy upgrading my HU on my 2004 54 plate Vectra SRi (half can bus)
Limit upto £200.

Also what does 'double din' mean?

I like the look of the double din ones....to fill the space in the dash properly.
Something like this http://www.caraudiodirect.co.uk/kenw...ve-p-7057.html

What adaptors would i need and what functions would i lose (if any) from the display?

cheers