There was a version of Norton, a recent one (with the internet security feature) which upon installing, turned off XP's default firewall.
If your Norton expired, or you had a pre-loaded demo version that came bundled with a laptop/pc, it would unactivate or if you removed it, it would LEAVE Windows XP's built in firewall DISABLED.
That's a very good example of why Norton is bad.
Norton used to be the cream of the crop, many years ago, but sadly in the last 4 years or so, they have gone downhill, very quickly.
The only thing they have selling their products is their previously good name and the fact that it still comes bundles with most new PC purchases.
I've been using AVG Free for about 2 years now, I've tried Avast, which is a good product, too.
AVG, in my experience, has picked up virii that a fully updated Norton AV has failed to detect, and AVG has remained cheaper, and if I recall, you get 2 years of updates, if you purcahse the full product.
Furthermore, AVG has discount prices for schools/NPOs.
/rant