well, obvisouly you didn't read my theory (itachi discussion, page 4), I think I explained it quite well there...

here are some main points of it.
Itachi knows who killed the uchiha clan.
Itachi can't beat that guy.
Itachi believes that Sasuke has the potenital to do that.
Itachi want to nuture Sasuke's hate to make him strong.
When time comes, Itachi will reveal the truth to Sasuke through the mange shiringan, as a sign of passing on the torch of being the heir to the uchiha clan.