If you don't intend to use your car on a road course, stay with you stock calipers and rotors. Get some Porterfield, Hawk or Axxis Street/Track pads. Ignore the rear brakes as they do very little. I have 80k miles on my SE-R which includes 4 track events and over 2 dozen autocrosses and the original rear pads are barely half-worn.
If you
DO plan to see track time, install NX2000 AD22VF front brakes. Thousands of words have been written on this on the SE-R mailing list, which can be found at
http://www.se-r-list.org/archives/, again ignore your rear brakes.
Only if you want the look do you go through the trouble of rear brake upgrade to disc. You'll need the rear hubs of B13 SE-R, the proper e-brake cable and maybe the B13 SE-R master cylinder and/or proportioning valve.