Pixiq

If you haven't watched any of Mark Wallace's tutorial videos, I think you're missing out. He tackles all sorts of questions with his series "Digital Photography 1 on 1." Here is a link to the first of several YouTube videos on Lighting.

http://www.youtube.com/user/snapfactory#p/c/BC5A73FEA8B7D7D2/31/rP9pluWiGCE