Well, I view impeachment from a different frame. I don't see it as a political proscription nor as a legal remedy, but I do see it as a remedy.
A cure, and maybe a prevention as well. Bush and Cheney are frightened, twisted men who have no morals, who share no values we recognize as truly "American," if you work through the American Mythology of our Founders; men who seek power as validation for their own insecurities and mortality, and it is a great and enduring shame that these men are the leaders of our nation, that they are the sworn protectors of our Constitution and our Rights, that these men are the face of America for the world to see, the face that all Americans look to to preserve and protect and foster the American Ideal, the truth that we are all created equal, and endowed with certain inalienable rights.
As Jefferson most famously said (my bolded type),
"...that to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed; that whenever any form of government becomes destructive of these ends, it is the right of the people to alter or abolish it, and to institute new government, laying its foundation on such principles, and organizing its powers in such form, as to them shall seem most likely to effect their safety and happiness." --Declaration of Independence as originally written by Thomas Jefferson, 1776.
It is imperative that we alter and/or abolish their governance of our country, to prove the lie to the Bush/Cheney/Republican prescription that the private sector can do all things better than the public sector, from prescription drug plans to natural disaster relief to war. As others have written, their "incompetence" masks their truer motives, devolving our government and its great Constitutional protections; and capitalistic exploitation on a grand and on a base scale the likes of which we have never seen in this country before.
They need to be impeached to stop the destruction they do to our future and our honor and our standing, all related concepts in our foreign affairs I add. And I disagree that the Congress can be a sufficient check on their greed and destructive actions, Bush has too many appointees, too many secretive deals with Corporate America to expect a Democratic controlled Congress without a veto proof majority to stop Bush and Cheney.
And perhaps more importantly, they need to be removed to demonstrate that what they represent is an aberration and a perversion of America and her values, that they do not represent Freedom and Truth and Inalienable Rights, Mom and Apple Pie, but the basest and darkest side of humanity, and that the American people will not tolerate that behavior any longer.