Remove Norton serial code

My previous subscription to Norton 360 expired, so I got a new one. The problem is that the previous one has been logged somewhere on my computer, because when I try to re-install it doesn't ask me for a serial code and just ends up expired.
So how do I delete it and use my new one?

>>14
If I have to keep my HD half full then the solution is a non-solution.

>>4
CA internetsecurity suite. They bought tinyfirewall which was the best security solution pre-vista. It includes AV, FW and malware shit.
You can download the 2007 Security suite on your local warez page.
For defragmentation use O&O defrag.