1) Draco still has both of his parents, he had to join the Death Eaters because Voldemort treatened him with the death of his parents.
Harry on the other side has no parents, Ron and Hermione aren't threatened and he has a got-to-save-the-world-and-everything-on-it-complex.
2) Draco bloks Snape out of his thoughts, he dares to imitate a dementor during a quidditch match, he shouts "you're next mudbloods" in a crouded coridor just after somebody was turned to stone... does that sound as somebody who is to coward to be a Death Eater if he wants to be one... _________________ Nederlands!!