I have a 430EX and I'm getting to buy a 580EX tonight when bhphoto is available again. I'm wanting to point these into umbrellas on some cheap tripods and use them to light a car at night time. I'm also wanting to do some model photography indoors with this setup. Can I fire the 580EX wireless from my 40d? Also, will 2 lights be enough for the auto photography? I just really want some opinions on this.