You can't win or lose an occupation, by definition. Its not a damned football game. Occupations have 2 realistic results:
1) Withdrawal of the occupying force.
2) Annexation of the target country.
a) Direct annexation - The country falls under total administrative control of the invading power.
b) Indirect annexation - A puppet government is left in place friendly to the invading power.
Modern history is full of examples from each case, especially the post-WW2 era. The US chose almost universally the Indirect Annexation option. But, the cultures being markedly similar between Germany-US and Japan-US, this proved to be a more or less smooth transition. The Soviet Union chose a combination of Direct and Indirect annexation, directly annexing bordering neighbors (Ukraine, Georgia, etc) while Indirectly annexing satellite states (such as Romania, Poland, Bulgaria, etc). China went exclusively for direct annexation of Tibet. France and Britain actually bucked the trend by total withdrawal from previously annexed territories.
Right now the US is failing because it is not pursuing definitively any 1 of these policies. We are extremely unfocused and dishonest in what we had hoped to accomplish, and the goals being set aren't realistic by any means. What does "winning" mean? What is the benchmark for success? Does the game end and a score come up at the end of 10 years and say - America 4540 points, Insurgents 3400 points, Iraqi people 60 points! At best, you could say we invented a new strategy called "Corporate Annexation" in which oil shills are installed as figureheads while contractors are paid to do not much to run the country's infrastructure. Meanwhile, the US troops have no clear mission except to stay alive, with an occaisional "Go get 'em!" mission thrown in for body count to raise that magic "winning score."
Or, if you want to say the goals were the following:
Enrich contractors and suppliers of war material
Multiply potential terrorists to perpetuate a "War on Terror"
Create a profitable environment for oil producers
Removal of a major enemy of both Iran and Al-Qaeda
Then we succeeded admirably.
The fact remains though that a majority of American people voted overwhelmingly to elect officials that would end the occupation in 2006 and investigate the corruption that lead to it. The Democrats are taking their popular mandate very seriously. To disparage a group of elected officials for performing the job exactly as the electorate wishes them to do it, methodically and responsibly, is to rail against the very foundation of our democratic society. The Republicans had a narrow popular mandate for 6 years and had complete control of Congress and the Executive for that time. 9/11 gave them even more popular support than usual. They squandered this opportunity horribly and at great cost to our treasury, our democracy, our reputation, and the lives of our people in uniform. They failed miserably in their duties as responsible stewards of our great nation and enriched themselves and their friends in the process, and then promulgated a propoganda war to cover themselves. This propoganda war still works on the bottom 30% of society, but is no longer effective on anyone with 2 brain cells to rub together. The American people voted for a change in the last election, let them have it.