Here is a good article about the whole issue of a good God decreeing evil by John Piper. I read it last summer and thought it was pretty good. Of course, there must be bigger and more scholarly works written by Reformed theologians on it.
Is God Less Glorious Because He Ordained that Evil Be? :: Desiring God Christian Resource Library
Also, I do agree with Pergamum that it is preferrable to speak of God 'permitting' evil and the fall of Satan than causing it. There are actually some hypercalvinist websites that will teach that God is the author of sin and causes people to sin. Like Arminianism, hyper-Calvinism is an attempt to do away with different tensions concerning doctrines that we find throughout Scriptures. On one extreme, one strain of Pentecostalism will teach that God and the devil are at war like two war-lords, which is obviously a rejection of God's sovereignty, and on the other one strain of hyper-Calvinism teaches that the devil is God's puppet.
I guess accepting all the teachings of Scriptures despite these various tensions is what true faith is about.