I would recommend staying away from Norton's. Some people still like it, others had had major problems. OS X has very good maintainance routines built it. They run in the middle of the night, so if you shut your machine off, you can change that or use a Cron program (http://www.versiontracker.com).
There are good programs available for OS X. Along with the built in, I use DiskWarrior, and TechTool Pro final version 4 is being shipped now.