I'm examining a copy of Michael McRobert's new book, "Beginning Arduino" and it is darn good. It's an expansion on the downloadable manual that he wrote for the Earthshine starter kit you bought. He includes a lot of theory, but he weaves it in perfectly so that if you feel like you understand the circuit and the code you can just glance over it, but if you are stuck and confused you can back up and easily fill in the theory until you "get it".