I wouldn't put so much blame on George Tenet until you have more of a concept of how our Intelligence System works, and not just based on the info that's popularly known what with the 9/11 commission and all.
I focused a lot on US intel and National Security while getting my BA in International Relations, and if anything, Tenet's one of the least to blame of anyone. Bush has done a good job of making him the scapegoat and directing attention everywhere else but home. It wouldn't have mattered who was in charge of the CIA at the time, they'd be in the same position, because the Bush admin. came in with their own agenda and ignored all other concerns/possibilities that conflicted with that agenda, and when Mr. Tenet failed to give the Bush admin the information they wanted, they simply sought such information elsewhere (Rumsfelt formed his own military "intelligence" agency during the lead up to Iraq because the CIA kept telling them there were no WMDs. When the cow won't give you milk, you go buy a goat...)
The head of the CIA's a bad job. No real power to oversee anything, no real influence, since no one will listen if they don't like what you have to say, and all of the blame if something goes wrong. Clinton couldn't find anyone else to take the job. Think Bush will do better?