Have NIS--got an offer for NS-- questions

OK, have some questions. I have been using NIS for a few years and I like it. I got an offer from Norton to D/L NS, for $19.95.

I chatted with CHAT, and found out it will D/L over my NIS and my remaining time will be added to NS (I still have 110 days left).

I guess my real question is: how well does it work compared to NIS? Does it look the same or will there be a learning curve?

In short, should I even do it?

Mel