Oh dear god please dont use either one of those products, mcaffee and norton are both extremely bloated ad/spyware hidden under the auspices of previously good products.
Download and install Avast Free version, Microsoft Security Essentials, or AVG antivirus. Personally i like Avast the best.
If you want to keep you comp nice and speedy download and install the free version of Glary utilities and run the 1 click fix every month or so.
for what its worth i did computer repair and pc building work on the side for the last 10 years.