The subject matter is always more important than if he did it under oath or not. At least to me. I don't give a rat's arse if CLinton lied about sex under oath or not. No one got killed.
As for Bush, if he didn't know then he is incompetent and has an incompetent staff. If he did know, he lied. In either case thousands died either by his idiocy or by his duplicity, in both cases, in my opinion, means he doesn't deserve to hold that office and should be kicked out of it.