To run HID, you need to have an H4 lens so you can replace the halogen bulb for the HID. A sealed beam won't allow you to do that, so I would suggest that if you want to run this eventually, that you grab a headlight with an H4 lens. I ended up buying a used headlight from a Sportster for my XS. (Sportsters and most other HDs run H4s) You just have to make sure that the actual housing is deep enough to accept the HID bulb because the bulb is a little longer and has wire leads going to it. (The HID has a little motor that flicks the bulb up and down for low and high beam.) It will look something like this:
I've bought my 2 kits from these guys:
www.v-leds.com and they have really come down in price. I paid $100 a year ago for my Honda, and $40 for my XS a month ago.
Otherwise, the HID setup is a whole separate system from your stock lighting with it's own harness and relay, but uses your stock headlight socket (what your halogen bulb plugs into) as a trigger and a switch for hi/lo. So basically, you run this harness from your battery to the ballast then to the headlight, and still get to operate it from your stock switch for high and low beam. Usually about an hour or 2 install.
I ended up getting the bright white 5000K bulb, because it offers the best visibility. The further up you go in the light spectrum (the blue etc) the less light is being reflected off of objects. Plus you don't look like some cheezy rice-racer Honda with a headlight out
Hope that helps. Maybe after my build is done I will do a write up on this.