HELP!! My Mini Schnauzer barks wildly at strangers and friends

by Dan
(Chicago, IL)

Hello.. we have an almost 4 yr old male mini schnauzer that is creating tension between my wife and I.
When our son has his friends over, he'll bark excessively when they arrive. When he does settle down, he may even sit with his friends. If they move suddenly, he gets agitated and will begin barking at them. One time he went so far as to bite one of his friends which has caused a rift between the friend and my son.
He did not break skin but I took this very very very seriously. It's to the point everyones labeled him as mean and stupid and it bothers me because he is a great companion and I dont believe for a second he's dumb..just misunderstood.. that and given the fact we never took him in for formal training.
Also, if he's in the backyard, and our neighbor decides to do some yardwork.. oh my god he will go nuts at them. It's a wonder someone hasn't thrown something at him because it is loud and annoying.
What can I do to try to curb this behavior? I've already called into some pet care places for dog training and will definitely look into this but what can I do for him between now and then? I feel bad for him.. I know he's a good dog, but enough is enough. I have to do something to correct this asap. Any input is greatly appreciated