Personally, I think that the "what's your alternative" arguement the lazy one. For example, in the recent war protests it's the people that positted that who now think "would you rather Saddam was still there" is all the justification they need.
That's too simplistic, if you are going to attack 'capitalism' per se, there needs to be a better reason than "I don't like it". Just as you exemplified the laziness inherent in: "would you rather he was here" is essentially the same argument as "if you are for capitalism you are also for sweatshops and globalisation"