Obviously downloading music is illegal, but if you actually own the CD, then I don't think it's morally wrong.
Yes its fine, you bought a 'license' to listen to it via vinly,cassette,cd,paid download etc and if you lost it I believe you can download a copy.
I see lots of products for sale to transfer cassettes/cds to mp3 so if thats legal, why not just download a copy of the song in the first place?
You are allowed under law the right to make a necessary backup and it is now widely accepted that people intepret this to mean ripping it onto an MP3 player or their computeryou buy a cassette you're entitled to listen to a cassette, you can't just walk into a store and pick up your cassette back catalogue on CD and walk out without paying saying it's OK, I've already got a license to listen to this music.
also regardless of what products are sold, it is still illegal, (at least in the UK) to rip CD's to MP3.
I can't see them prosecuting you though if you have all the original CDs and you download some MP3s...
but I also can't see why you'd want to bother wasting your bandwidth when you could just rip your own CDs.