if you have bose get an amplifier(adapter from halfords £45 ish) otherwise the front speakers wont work and u need a decent headunit not a ****** ripspeed one lol, i recommend pioneer, alpine or kenwood(top spec) for a good flip out screen!!!!!!!!
Cheers mate. Gave autosounds a call and im just going to put it into their hands so atleast i know that its going to be done properly. As the last time i put a hu in a car it didnt go too well.. ask hardy haha
As far as interfacing the HU with the PS3, you'd need to make sure that the HU takes s-Video and Phono inputs. You can then use the additional cable that comes with PS3 to connect it to your new HU.
As far a replacing the standard HU, your looking at using some sort of adapter to mate it with the weird Bose speaker/amp wiring (I'm assuming that this is what you have on your S3). You can find some examples on this site, but you'd need to make sure that the adapter is the correct version for your particular model. They are crap and if you are after good quality sound, then ditch the standard wiring/amp/speakers/sub and replace it with something that actually sounds half-decent. AndyMac on this site is THE man to speak to about Audi sound upgrades.