What are We Fighting For?

So I was watching meet the press this morning, and the host kept talking about how George Bush desperately wants to win the "war on terror". Rudy Giuliani was being interviewed on the show and he talked about how McCain, if elected would win the war, as he was always supportive of the surge of troops to Iraq. Rudy was also talking about Obama's will to lose the war. How Obama, by wanting a time frame to withdraw troops during his presidency, is willing to give up and lose to the Iraqis. Mind my ignorance, but what exactly are we winning by staying in Iraq? What are we even fighting about anymore? I mean, I know that the initial reason was to eliminate nuclear weapons (which never existed), then to eliminate Saddam Hussein, and then to "create democracy" within Iraq. Because I'm pretty sure we accomplished most of these things, why are we there now? I really would like to know. Comments? Answers to my question? I honestly have no idea.