As a thumb rule; is it sold in a shop, then it most likely is protected by copyright laws. Smash hits, blockbusters, or the top of the bilboards fall definitely under this category.
However, copyright laws depend on the country you live in. Some allow you to download a song of which you've already legally bought the CD.
Other than that, just use your common sense. Just don't believe that with purchasing the LW P2P client you'll also have purchased the right to legally download copyright protected material. That's definitely not the case, besides when downloading LW you confirmed already not to do so (remember?).
