DAve -
RE: your question of how many lights to use - I don't know how many of these bulbs for sure, but one of these along with a shoplight with two "daylight" flourescent tubes and some ambient light works pretty well for me. It's a strong light - I would think two, even in a dark room, would be sufficient. I used it by itself yesterday in a room with minimal daylight to give sufficient light at 100 ISO.
Kim - my goof! It's been awhile since I looked up the post - it was Chris Saper. Sorry, Chris! Here's the link:
http://forum.portraitartist.com/show....1000bulbs.com
Julie