Fluctuating download speeds on new laptop?

I would uninstall Norton and install a Free alternative like Avast or AVG. Are you connecting via wireless or direct with a cable its possible that you are getting interference on the wireless due to your neighbors routers being on the same channel one way to check this would be to hook your laptop up directly to the router and try downloading something to see if its any better or not if it is better I would log into the router and go to the wireless settings and change the channel settings to either 1 or 11 or set it to auto