If you know how to edit the registry a format isn't *usually* necessary... however, you can google Norton removal tool and it will save the hassle.
I personally hate the likes of Norton/McAfee/Bullguard etc.. the only reason they exist is for the likes of PC World to sell their PCs/laptops...
Its difficult to know which to do first, Rob....

...
Format the Hard Drive first...
....or...
Format the Hard Drive after you've cocked-up the Registry by fiddling with it!...

...!
...LOL...

...!
Paul...I hate fiddling with things!...

..
...especially when it results in a slap around the face!....

...!