Even though you own the original disk it's still illegal to download an ADF - you could have made an ADF of your own disk while it was still working, but downloading an ADF of someone else's isn't allowed.
That might be so in the usa, but is not the case here.. You should not need to pay twice for a copy that you already own.
It is virtually impossible to get a working orginal copy these days anyways... It is suprising that his orginal floppy has lasted as long as it have. If everyone thought like you, then all this software would end up getting extinct.