Internet security upgrade or new package?

Hi there, 

 

I have the internet security 2010 package wich i should renewal very,very soon. So i went to my local computershop because i like them. But i had a question they could not give me an answer to.

 

Can i buy the Norton Internet Security 2011 3-user upgrade (PC)?  

Or do i have to buy the full package and not the upgrade? I don't understand it. There's a 10 euro gap between them .

 

 

Please help and advise me.

 

Greetings, 

N.