Well, in the US it is very very legal to make copies once you buy it. Also, not mentioned here is the legal precedent set by the courts in interpretting these laws. Generally, unless you are making money off the copy, OR hurting the business of the copyright owner, THEN you are no longer covered under fair use. SO, I think that in the case of the download, the court would find that:

• You did purchase license for the work
• You were not reselling it, or showing the copy
• You are not costing the publisher anything, so there is no harm. Harm must be demonstrated to override fair use.

Also, the idea you can only copy part of it, that is actually, you can reproduce only parts for distribution but in fact you are allowed to copy the whole work for personal or academic use.

You would have a difficult time finding a judge in the US that would care if you had physically made the copy yourself. For example, if you pay somebody to make you a copy for personal use, neither of you have violated copyright law, even though the person who actually purchased the book isn't the person who made the copy. Generally, US copyright law doesn't consider the physical aspect of the copy, but rather the content. That is, it is not the paper with ink that is copyrighted, it is the pattern of words that is copyrighted.
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