Another person here who will not use Norton unless, like now, it's already installed (a friend gave me this one since mine is down), and then I uninstall everything but the AV.
Most of us here use AVG free edition at www.grisoft.com, or, if you must pay for AV, most everyone here will recommend NOD32 at www.nod32.com. You can use it for a month free trial.
Actor Kevin Kline was asked once (Actor's Studio) how he can play his comedy rolls with such repeated and consistent passion. His response:
"I don't know, I just can't imagine not being happy."