Mild Autism?

Hi all, my youngest son (of 3) has just been diagnosed at the age of 5, with an Autism Spectrum Disorder. I'm probably in denial, but everything I read doesn't seem to quite fit with him. He is fairly repetitive, likes to watch the same DVDs over and over again, sticks with the same friends and isn't at the same speech levels as friends - but he is doing ok at school, is very sociable, perfectly happy at playing imaginary games, has no behavioural issues to speak of, is no less empathetic to peers or parents when they are upset. All of the literature that I read seems to be geared towards more severe cases, and I'm struggling to put my finger exactly on what it is he can't do that other children can do, and so what support I can give him. Are there any good books or resources out there for children with more mild autism?