As for going to OEM halogen headlights, there will be a bit of work involved. They both use different plugs so you'll have to cut the the existing plug and wire in a new one (not recommended) or make an wiring adapter to go between the two (recommended).
Alternatively, you can purchase aftermarket headlights that are already compatible with your HID plugs.
Hatch Nation #13 : Rally Revolution #13 : ROTM Jan '13
I drive a bobble, a square, and a rectangle