One of the basic flaws of going to war in Iraq was not the decision itself, but the way in which it was sold to the public, something I argued a lifetime ago in Iraq: A Venture Pitch. The reason I bring this up again is that the entire left to right commentariat is weighing in on the Downing Street Memos and the opinions range from the poor and predictable 'impeach Bush' to the informed and sober 'what's new here?'. The latter position seems to be the most compelling one and Jeff Jarvis sums it up nicely:

Of course Bush had decided to invade Iraq long before he said so. No one is surprised by that. The scandal here is not that he invaded Iraq -- a policy decision about which reasonable and unreasonable people can disagree -- or that he was determined to do so as soon as he took office -- what politician doesn't have hidden agendas? -- but that he did such a bad job selling it before and after the fact.

In fact there's a vast array of books and articles widely available which document the decision path leading up to the war as well as a description of the planning that was involved in it (Tommy Franks' American Soldier comes to mind). Again, you can fault Bush for delivering the wrong speech, you can fault Rumsfeld for allocating insufficient troop numbers, but neither the US leaders nor their British counterparts ever acted in bad faith in ousting Saddam.

More here.