Viruses are alive only insofar as they have DNA can reproduce. However, they cannot reproduce without a host cell, or metabolise. They can also survive crytallisation which is a characteristic shared by no other organism.
I don't think that viruses are really "alive" or "non-living" , as such. After all, it really just depends on your definition of what is alive. This is kind of arbitrary as scientists don't agree on what 'alive' actually is. Therefore if you think reproduction counts as alive, then they're alive, but if you think they need to be able to reproduce independently, or have a nucleus, then no. It all depends on your conditions for life. I think they will remain in a grey area between living and non-living, at least until a more rigid definition for life is established.