Don't get Norton! That went from a good A/V software to one of the most bloated and useless pieces of software crap out there. (I blame Semantec, they F' everything up.)
Get NOD32, or AVG, or something OTHER than Norton, McAffee, or Trend Micro. Because those three are the big anti-malware programs out there, new viruses are writted to combat them, so they will miss 80% - 90% of new malware. THis means that while other less popular anti-malware programs may catch a new virus, you have to wait for the big three to capture the virus, dissect it, and then release a fix for it.
Not to mention that they're f'n expensive.