Serious Bedtime Tantrums?

My son is 28 months old. Every night we have a routine for bed like all the books say. First we take a bath, then jammies, we relax and read a book, and then time for bed. He is so good and lovely until it's time to sleep. The minute he hears bedtime or anything that insinuates time for sleep he begins to cry and then this whining cry turns, very quickly, into a shrill scream. When we lay him down he kicks, and even when the screaming and whining dies down (fifteen to twenty minutes later) he kicks his legs around. Some of my friends who have children tell me that the tantrum dieing in twenty minutes is a good sign, but i feel terrible letting him scream. I would agree with it being a good sign but this has been going on for about a month now. We have tried calming him down, we have tried letting him cry, we have tried letting him know mommy and daddy are tired too. All these things are fruitless efforts. My child still flipps-outight. I am so frustrated by the end of the night i can't see straight. I feel bad that i get upset because I know my son isn't doing this to upset me, he just doesn't want to sleep. I feel like a failure. how do i help my son sleep and go to bed calmly in any sense of the word. I would settle for anything but screaming and kicking.