The best brand/combo is a Hella or Philips ballast/ignitor with Philips bulbs. You get what you pay for with these.
Two sites I highly recommend are
www.hid-online.com and
www.xenondepot.com
Titan Before:

Titan After:

Accord Halogen on left, Titan HID on right.
I also wouldn't go above 6000K color temp (Philips actually stops at 6K)
My kit is Hella ballasts with unknown bulbs I guess @ 7000K...the ONLY reason I got them was because they were DIRT cheap. As you can see, the light output still looks white on the ground and if you are looking head on....however, if you look from the side it looks a little blue. I've never been flashed and never had a problem with the police...just re-aim your headlights.