Ditch the Norton, it's a resource hog. The prior recommendation of nod32 is a good one. A few good choices are Trend Micro, Norman, and Panda. Also stay away from McAfee, it gets into too many things and is just too problematic. People can sing whatever praises they want for free antivirus, but I'll stick with a pay program for better protection and more features. Yes, I have seen Norman find viruses and trojans that AVG and Avast did not. Think about it, these people also sell other versions of these programs. If they gave you everything for free, who would ever pay for their other versions.