Part of being an American is dissenting when you don't agree with the politicians. Countries that require total allegience to a leader are not like America. Many of us feel that in order to be loyal to America, we have to get Bush impeached, or at least make sure the PNAC neo-con group is ousted from power in the next election cycle..
I, too, would support whatever my military commanders would tell me to do; that's part of being in the military. Including going and doing my job in Iraq, despite my feeling that it's an illegal and amazingly stupid war based on lies. When you sign up, you promise to do your job, not follow your own whims. I admire everyone who's done this no matter where they served or in what era.
Service to your country comes in many forms, however, and one of them is housecleaning, which we need badly right now, in my opinion.