Just to correct. Annihilation is not really the correct term
although some may put it this way, because there is no existing
self in the first place, even right now as I talk to you.
On conventional sense, to reach nirvana, other than fully realising
the truth of emptiness, one has to clear one's fetters. (one has to
clear 10 fetters before attaining Arhantship) Or one can say greed,
hatred, ignorance is completely destroyed. An Arhant will stop
returning to samsara. A Bodhisattva although realised the truth
returns to samsara to help others.
But one can also say, as the sutras point out, Nirvana has four
characteristics: Eternity, Bliss, Self (different concept and does
not contradict "no-self" ), and Purity.
Sorry, no more off topic.. (more info refer to my forum) you all
continue discussing 
