Harm
I'm building my concept of morality on harm done to another. If the "victim" is completely unaware of the act, and it does not harm him in any way, it is difficult for me to recognize the element of immorality, other than through simple intuition, and that is not sufficient in my opinion.
That's not intuition, that's your conscience talking. ;)Sometimes if an act feels wrong, it's because it IS wrong.
I'll grant you that if you download a couple of Madonna songs, or entire CD's for that matter, that you weren't going to buy anyway, you haven't by that act alone caused her any financial harm. However, if you grant that she has a right to control the disposition and use of her property, then your act in a small way is violating her right. So even granting that you have "perfect knowledge" in this argument, and no one downloads her songs other than people who would have bought them anyway, the downloading still causes harm. It's a teeny tiny harm, sure. Of course, if you don't recognize any moral justification for ip rights at all, even limited ip rights, then there is no harm whatever.
As for this statement: "I'm building my concept of morality on harm done to another," aren't there plenty of instances where an act would be immoral even if it doesn't result in harm to another person? What if you drove 90 miles an hour through a crowded parking lot and manage not hit anyone or anything? You haven't harmed anyone, but that doesn't mean your act wasn't morally wrong, because of its potential to cause harm.