Just watch the video I described. That is all I am talking about. He is right about technique being key over power. The thing is that he is just trying to get you to not muscle the ball. It is rare I see any rec player who does not muscle their serve.
Of course if you have that technique down and add muscle, you will only improve your strength and play better. But good technique will give you a loose arm, which will give you a real serve. That is the main thing to focus on first.
Please help TT Member BruceD get a wheelchair so he can play tennis again - http://tt.tennis-warehouse.com/showthread.php?t=496820