Cart before horse :) (House)

I'm about to buy a house which is seriously "wired" and I need to know the best way to use it.
The property has
Cat5 in every room taken to a central location
Speaker sockets in various locations downstairs also wired to a convenient location. Also some ceiling speakers.
Tv satelite sockets in various locations taken to a distribution amp in the roof space which also has the feed from a dish
Super fast broadband
Centralised vacuum system (less relevant but it sets the scene)

I also have a pair of humax satelite systems and a couple of smart TVs

So.... Ideas on what to do please ! Not sure what I want...but I want ideas
Gerry