Excellent arguments. I enjoyed reading every word.

Copyright infringement is illegal, but I could argue that the majority of my music files or not 100% duplicates of the original.
At least have my files have been shortend or just plain sound like an 8-track. When Puff Daddy remixed 15 out of the 16 songs on his album all he did was change a couple beats, words, etc.. He did not make a 100% exact copy: Therefore avoiding copyright infrigement.

Suppose I only download files that are 99.9% original would I be infringing on copyrights???