norton's a resource hog.. and at the moment, the auto-protect on my trial version takes like 3 minutes to enable, and screws up any usage of Outlook during those 3min.
I've manually enabled it every time, and on every next startup, it's disabled for the first 3 minutes. SUCKS!
I'm considering using PC-cillin, i hear it's good. Also Avast seems VERY popular over at download.com
Used to use AVG, but it missed a lot of scripts and trojans on my old computer.