I dont agree with the war either, but thats not gonna stop me from doing my part. For every draft dodger the military has to find someone to take their place. I just couldnt sleep at night if i did that.
If the US was in imminent danger of attack from a hositle, outside force(that we didn't do something stupid to piss off: see Iraq), then I would join up, too. However, I would resent the implication if someone told me I had to join up and fight. I am not obligated - I am not forced - to do anything; if I go into the armed services, it will be of my own volition, in my own interests of seeing the country defended.
Not only is the draft blatantly unconstitutional, it also contradicts the value of freedom. A country is not more important than the individuals that make it up.