I came across an interesting site with a lot of good information about automotive headlights. There is a lot of information at this site that would be useful to anyone wanting to upgrade them.

The URL is (no "w's"):

http://lighting.mbz.org/

Myths are dispelled about the new “blue” headlights bulbs - why they are a waste of money and why some people (especially kids who want to pretend that they have the high-end HID lights) incorrectly believe that they really are an improvement.

There is also a good section about problems with HID lights (compared to halogen there is reduced distance perception, more glare to on-coming drivers and backglare to mention a few), as well as why a car should not be retrofitted with them.