From my POV, the pay-for-music thing best exemplifies the difference between possibility, legality and ethics.
Is it possible to avoid paying for music? Sure it is. Many people do it, and almost all get away with it.
Is it legal to avoid it? Slightly unclear -- the laws are rather subject to interpretation, and there's a lot of sloppy space between that which is clearly legal and that which is clearly illegal. It's probably illegal, but enforced even less than the traffic laws.
Is it ethical? Well, there's the rub. IMO, if the artist created the work with the desire to be paid for it, then it's unethical -- wrong in the purest sense of the word -- to not do so. And for me, ethics is really the important bit, far moreso than legality.
Of course, a lot of that is pretty grey. If the money for a song was entirely going to the artist, I'd be a lot happier than knowing that most of that money is going to a studio that takes a wildly unfair cut. Still, there's a world of difference between the artist getting less of my money than they should, and getting none.
And ethics have their limits. My rule of thumb for all software (of which I consider music to be an example) is, "If I can afford it, I should pay for it." I try to take an acid but realistic eye to affordability. If they charged ten cents per song, I would feel utterly obligated to pay. If they charged ten dollars, I wouldn't feel terribly guilty about just downloading it. The current market rate of about a buck a song is pretty well-placed to be about the most I'm willing to pay for a single song. Frankly, I'm hoping to see some price competition as the new model comes in. Once the studios start breaking down (as I think they will), and the now-less-useful middlemen start taking smaller pieces of the pie, we'll hopefully start to see more good songs going for a quarter each, with most of that going to the people who really deserve it: the artists.
But price issues aside: I really do think it's unethical to use intellectual property without paying, if it's within your capacity to pay. Being in the software business myself (in multiple capacities), I'm very sensitive to this...