Complete Removal and Reinstallation of NIS

We use Norton Internet Security on our computers.  NIS is not operating properly on one machine.  I would like to completely remove and reinstall NIS on this machine.  I have a couple of questions to ask about the process:

1). Is NIS best removed via the standard Windows Control Panel "remove program" option?  Or is it better to use the Norton Removal Tool?  If I try the Control Panel approach first, how can I tell if I still need to use the Norton Removal Tool? 

2). Since we are removing/reinstalling NIS on the same machine, what do I need to do to keep the license intact so I can reinstall the program?  What do I need to reinstall the program *from* (e.g., the original program disc, a downloaded file, etc.)?  How do I then access the license that was originally on the computer so I can install NIS again?

Thanks very much for your help with this.