Someone always jumps in and says this in these threads; so it might as well be me :P
I surf, email, game, research, Google, blog, bank and shop on-line. I do all those WAY more than the average person; and do them WAY more hours per day than the average computer user.
I've NEVER run an A/V program of any kind... other than downloading something like AVG now and then for a scan to satisfy curiosity.
I DO run Adaware and Spybot, regularly.
I've never gotten a virus, worm or bug. (except once.. and we won't talk about that, 'cause I know how, when, where and why I got it

)
Never open emails from people you don't know. Stay away from icky web-sites and never insert CDs, DVDs or floppys that you aren't 100% sure of, safety-wise..
You'll be just fine ;)