Is that the one where he announced the creation of Homeland Security, given before both houses of Congress? If so, as much of the speech as allowed is on CNN Tribute: America Remembers: The Events of September 11 and America's Response. Very excellent look at the tragedy, how it affected the nation. The speech is a bonus feature. More info at http://www.cnn.com/americaremembers
Very highly recommened, especially as a historical archive for children who may be too young to remember, or understand.