The "metabolism" requirement is an important one, though. If you remove it, and you allow for "self-replication" that's entirely dependent on an external agent, then it seems like you would have to consider all kinds of things as "alive" that would fall outside any common-sense definition of the term. For example, works of literature.
It seems to me literature doesn't self-replicate, we replicate it... And apart from the bible and such, literature usually dies out fairly quickly in the grand scheme of things.