Wel I think the first mistake you made was buying Norton Internet security. There is plenty of FREE PC security software out there so no need to buy any security software.
You dont say if you bought it new from a online shop like Amazon, or second hand from ebay or similar site so not sure if the fact that it is open is bad or not.
If it was second hand someone may have already installed it and used the license.
The fact it says "System Builders Edition" means it was meant for someone who was building a PC (maybe a large company like Dell, or a small computer builder).
This differs from the Retail version that is sold in a box in places like PC world.
You may find the support options are different for the System Builder edition than the Retail version, but I dont know enought about Norton's products to help you in that area.
Here is the support page for Norton System Builder.
http://www.symantec.com/partners/programs/chan nel/detail.jsp