Hi, ppl and systems administrator here, my advice is just get rid of all commercial stuff like norton, panda, etc. They just pay to be on the top of the list on magazines' reviews, and the bad boys who don't like this behaviour build viruses specially designed for norton and co.
A free antivirus like AVG or freeav and an antispyware like spybot or windows defender and the default windows firewall it's all you need to be safe and fast. If you want a commercial solution then I recommend the TrendMicro PC-Cillin, it works fine.
Best Regards.
Diego