Norton Security Verification is an old product from Verisign rebranded by Norton.
Make sure to understand which seal you’re buying from them.
A Norton Secured Seal is only shown to users of Norton Internet Security,
Norton 360 and Norton Safe Web Lite in their search results pages.
Sites that display Norton Secured Seal use VeriSign SSL or the
VeriSign Trust Seal which indicates that their business has been
validated as a legal business entity and the web site uses recommended
security practices including best-of-breed SSL Certificates and daily
web site malware scanning. To find out more about VeriSign SSL and
VeriSign Trust Seal.
Criticism : It’s like DRMs they add a lot of hassle for the owner and do not stop the people who want to cheat.
In this case you are not really protected and if for whatsoever reason your seal become invalid, welcome to the land of Norton administration process (or any vendor of seal for that purpose).
However on a user perspective : security seals still seems to work well like CJFranken and JohnGB pointed out.
From my personal experience : on an e-commerce website selling flights to Canada from UK, we did various A/B testing such as "text seals" versus the seals with their logo. Then no-seals vs text-seals and no-seals vs logo-seals.
Each seals had a link "check me". From the stats, very few visitors clicked on those links.
The conversion rate always been much higher with the page with seals and their logo.
This experience was set in this particular context : selling flights. The seals displayed were the one from Verisign and the industry sector ones : ATOL, ABTA, IATA.
There is non scientific literature on the web where security seals do not always win the conversion :
Looks to me it’s not the security you’re buying, it’s that fact you can put an image of a trusted brand on your site and it’s dependent on the context of the call to action you’re looking for.
On any case Norton is a trusted band and they are nagging users on almost every new Windows PC. I don’t think there is much confusion between Norton and security in the mind of users.