Norton Internet Security is good - but I find it too good. It
slowed my laptop down to a crawl.
After my subscription expired, I uninstalled it and downloaded AVG
Antivirus and ZoneAlarm Firewall - both of which are free.
My laptop's faster now, and just as protected. Just take simple
precautions like not opening suspicious email attachments or going
to *ahem**ahem* websites, and you'll be just fine.