Hi there! Done this myself early this year!! - makes a nice difference!!
You need discs/pads/calipers/carriers (get the steady springs too!!) and its a straight swop of parts and a quick bleed !!
I confess I used new pads/discs (groved and drilled) for the look of the thing!!
You will be stuck with using 18" wheels from then on mind!! (apart from some very rare 17" that were mostly fitted to the V8's I belive!!) no 16" with cheap winter tyres!! - Oh and if you get a front puncture and you have a space saver spare you have to fit that to a back wheel first and move the alloy rear to the front!!
HTH??
Andy