If you don't fancy manually going into your registry to remove certain items, (it can be rather tricky if you're not used to it), there is also Symantec's removal tool to be found here:
http://service1.symantec.com/Support...05033108162039
Having never had Norton for years I can't vouch for the tool to be 100% effective but I reckon it might do the job.
Can I ask Shape, what AV are you replacing it with?