Norton eats a VAST amount of system resources. Mcaffee does too. Neither will fully uninstall from your machine and require you to spend time both sorting through and deleting dead directories on the hard drive and scanning/deleting registry keys. In addition, there are a very large number of virii out there which target Norton (or Mcaffee, or both) directly, rendering them useless and opening your machine to further malware...
i agreee ,and personally i think the best AV is the one that keeps updating very very frequently .i mean even before the virus are out. :-)