Stock headlight housings that are the "bumpy" type are the ones that aren't not made for HIDs (they separate the light beam into millions of tiny beams going in all directions), but most aftermarket housings should be fine for HIDs. I know tuners has a shitload of threads on people doing HID conversions, and IIRC, they even have a tech article about it. I have it saved on my laptop, so when I get back on that baby, I'll post up some links and what not.
EDIT: I think this is a little different than what clipsekid did, but these are the actual real HID projector and ballast retro-fitted into a projector housing instead of just a plug 'n play system.