Where do they disagree with Cheney?
Cheney thinks the war is nearly won and over, but still wants to keep troops in Iraq at the current level, and would like to keep them there for as long as possible.
Cheney still insists that there was an urgent need to invade Iraq, despite the nonexistence of the alleged WMD's.
Nunn and Powell said that a case can be made for not invading in the first place.
There are several other points, and you can find these out for yourself.