Here's the procedure from Bruno's site for the 9005 conversion. It works best with a dremel, but it can be done with a utility knife. http://www.bmwe34.net/e34main/upgrade/more_light.htm
The bulbs you choose to use is up to you, the Sylvania Cool Blue works well, and then there are more expensive bulbs to choose.
Essentially, you are using an unshielded bulb on the ellipsoid light (which has the shield built in) it does make a big difference. You should re-aim your headlights after installation. Aiming procedures can be found on Bruno's site also.
Hope this helps...
JR