I too have been using Norton Antivirus for several years now with no probs. Only thing is I always buy the CD for a little bit extra so I can do an add/remove if things go wrong and don't have to waste time fiddling around on the internet. Curious to know - why you also use the Norton Firewall? Is it because it plugs more gaps/holes than Microsoft's Firewall (pardon the simple language)?
With my first Dell, Norton came installed. When something went wrong I ended up talking to a Symantec chap in Holland who explained that Dell only put on a skimpy version of Norton. He advised me to buy the full version which I did. I wonder could that be the reason some posters are having trouble updating NortonAV? Norton only updates once a week - late Wednesday nights - at least that's been my experence. And no virus has ever slunk in - touch wood.