I would comment in an email to Rachel, but I really something to blog about. This is something that comes up a lot in Catholic circles, and I actually find it interesting why it becomes so heated. Very often I find it is used as one of those "good Catholic" litmus tests, i.e. "You allow your kids to watch Disney? We never!"
I actually do not believe that the few people who stop buying mega products like General Mills cereal, or stop buying Disney tapes do much economic harm to a company. I do feel, however, if you know a certain company strongly backs a view you find contrary to your beliefs, you certainly don't have to give your hard-earned money to that company. That's your prerogative.
I think it gets sticky when people start expecting others to start rejecting Cheerios or Stoneyfield yogurt with them. It is hard to find the exact companies that give to Planned Parenthood for example, and start abandoning them all. Not impossible. Just to me, it takes much energy that I really need for other things.