Viruses: Genisis and Classification

[AJ Boulay]

I am interested in the genisis of viruses and thier classification as a 
living organism in it's pre infection form.
I understand that viruses are inert until they can combine thier DNA with 
that of a living cell.
My question's are:

- are viruses still classified as viruses after infecting cells, or are 
these cells simply classified as malignant? 

- If infected cells are not classified as viruses, how is it that viruses 
come to be? If they are inert they do not have metabolic processes or 
division.

Thanx,

AJ