What's it Take to Win in Iraq?

According to Slate Magazine, General David Petraeus in his counterinsurgency field manual seems to indicate that the forces supplied for The Surge™ are way below what would effectively take care of the Iraqi insurgency.
One point they made is that it requires a lot of manpower—at minimum, 20 combat troops for every 1,000 people in the area's population. Baghdad has about 6 million people; so clearing, holding, and building it will require about 120,000 combat troops.

Right now, the United States has about 70,000 combat troops in all of Iraq (another 60,000 or so are support troops or headquarters personnel). Even an extra 20,000 would leave the force well short of the minimum required—and that's with every soldier and Marine in Iraq moved to Baghdad. Iraqi security forces would have to make up the deficit.

In the short term, then, say for a year or so, enough troops might be concentrated in Baghdad if troops now deployed in Iraq have their tours of duty extended, troops due for redeployment to Iraq are mobilized several months ahead of schedule, nearly all these troops are transferred to Baghdad, and enough Iraqi troops can be mobilized to make up the remaining slack.

It seems we as a nation have 2 choices: 1) Cut our losses and leave Iraq, Mission Accomplished-style or 2) Invest more money (and American bodies) than we can possibly afford to force democracy on Iraq, meanwhile bankrupting our country. You can read the entire article here. Also, if you'd like a free copy of Petraeus' manual, go here.