I have 2 computers and a laptop, actually, all of which have net access... and I have a metric ton of stuff to potentially lose (and stuff even that cannot be replaced)

But the answer isn't keeping my machine offline - its in doing frequent backups. I have an external drive, and a server with unlimited space. Ive had my runtime going since Poser 4. And with that setup? My old machine ran 3 yrs without one single virus.... my new rig.... no viruses, either.