Depends if you want a mining-only rig, or a workstation that packs enough power to mine I would say.
Anyways, the
only thing you really need to mine is a (several) high end AMD cards: the 58XX line, or the 69XX line; a PSU that can handle them, and enough air flow to handle the heat. The rest is irrelevant.
The rest is entirely up to you. If you plan to recycle your mining rig into a gamin rig, get yourself a nice CPU and a case to go with that. If not, get a celeron and a pizza case
