Can I recommend Freeing Our Families From Perfectionism by Thomas Greenspon?
http://www.amazon.com/Freeing-Famil...p;s=books&qid=1257971129&sr=1-11DS7 is perfectionist. His perfectionism peaked when he was in K in Montessori. It was a disaster. I too was worried its role in homeschooling. To my big surprise it got better. As long as he has a challenging material he is fine. For him it's ok to make mistakes when he is learning something new and difficult.
One of the high points of the last year was when he said that getting 90% (or may be even lower) on a difficult test was good!