Keef,
I'm in a very similar position - I was also getting several hundred spams a day until Demon starting filtering them a couple of years ago. I'd say I get sent a virus in an email at least once a week, and in those cases I generally get the same email arriving at three or four of my email addresses at the same time. However, one doesn't need AV software to avoid being infected by a virus delivered in that way.
I completely agree that AV software can be a valuable safety net for less aware users, but I wouldn't agree that it is always true that not running AV software is foolish. One wouldn't suggest that a PPL student with 10 hours goes off solo to have a go at spinning, but that doesn't mean that spinning is off-limits to everyone.
I also have a cynical side, which leads me to believe that the multi-million dollar anti-virus industry has a vested interest in scaring people into buying their products, so I tend to trust my own twenty years of experience over Symantec's marketing department....
