If you haven't seen this video, I HIGHLY recommend it. It's a little long, but this is the very best information I have seen on this topic!
[video=youtube;6wXkI4t7nuc]http://www.youtube.com/watch?v=6wXkI4t7nuc[/video]
[video=youtube;6wXkI4t7nuc]http://www.youtube.com/watch?v=6wXkI4t7nuc[/video]