Jaxson: Whether you opt for your satellite speakers or in walls etc, the pre wiring will be mostly the same, assuming you're likely to mount either in the same general location. I'd run a few extra cables to allow for a 7.1 install at some stage in the future, ~ just leave enough in the wall cavities to be fished out at a later date if required.
Also think about the sub location, either pulling an all in one pre terminated sub cable, or some RG59 coax you can terminate yourself later. Your sub will need a power outlet nearby too.
All the usuals from there, as in if you're wall mounting a TV then ensure you get in now with some additional bracing to hold the tv mount and allow for an electrical outlet up the wall to power the TV. Give a lot of thought to where your receiver/bluray player/freeview PVR is going to be physically located. You'll want to run cables from the TV location back to this gear, so you'll want a heap of connectivity options between there. Also some ethernet cables if you're looking at connecting data to a TV/PVR/Bluray player etc, either now or in the future.
There are other posts on here about faceplate outlets for this sort of thing. I'm big on one cable between two devices so I'd look at brushed faceplates etc, but you can install terminated face plates if you desire, and run fly leads between the device and the wall. It gets more involved if you're looking at putting everything in a cupboard quite a distance away from the TV etc.
Thanks for those pointers - I think I have almost all of the other stuff under control, just the speaker placement is making my head spin with the options. Definitely have the networking / TV mounting thing all under control.
The wife is now interested in in-wall / in-ceiling speakers because of the look, but it's a bit of a gamble as I'd no doubt end up buying speakers online without being able to listen to them first.