Usually biologists use the following criterium to distinguish between live and non-live matter: ability to self-reproduce. Now, viruses are not capable of self reproduction without external help. Thus, they are not life yet? On the other hand, if to broaden the biological definition of life from self-replication to replication in general, then computers or cars are alive too - because they too are capable of replicating (although with external help - like viruses). Or shall we say that cars and viruses are sorta 30% life and 70% not life?