Kristen:
As the author of "LightWorks in Archicad," I don't believe him either. Perhaps buying the DVD will provide the answer, but you can get high quality rendering information in my book at much less cost. And I freely share my information on the forum.
You problem is that Window Lights do not actually light the indoors - they just make a glow on the ceiling. They will be your time eater.
The window light is a dangerous light source because as you increase size and quality of its output, the number of individual light sources contained within it grow. You can anticipate this using an isometric preview in the lamp object window.
Use a general light source or a light cone down to illuminate the interior. Like in my book.
Quick renderings - use a tiny window.
Dwight Atkinson