Originally Posted by Rose
That's the correct order.
You won't find Halo 2 on there since it was for the original xbox, they'll probably do a remake of it soon though to cash in on it since it was the most loved multiplayer from what I read. (that's the only one I never played online so I have no clue)
Gamestop, should have it cheap
Rose is right. However, I'd strongly recommend Halo CE as the starting point. You'll have a clearer/better understanding of the events in Reach.