We've finally actually entered the era of computer viruses. After all the years of hype, we're now at the stage where viruses are becoming a common occurence. I've avoided infection myself, but we've had a couple of cases of people e-mailing us viruses (entirely innocently, of course) - most recently BadTrans. I also talked someone through the process of removing Navidad earlier in the year.
Viruses have always been around. But they've usually been low-impact, not really spreading, and caught by people before they caused too much damage. This is changing.
There are a few basic precautions that I take.
There are probably other things I could be doing, but this has seemed to work for me so far.