Is it legal to copy someones cd's to your computer?
does the cost of the original cd enclude giving it as a MP3?
Burning it to your own computer for personal use is fine - sharing it with others is illegal.
Not if you aren't paying them for it. It shouldn't worry you too much as long as you don't advertise how you got it.
we should ask ourselves also, "how do I feel in my heart about this?...;-)