Dell isn't too helpful with looking up someone else's models, so it's not surprising I didn't find yours.
If you have Norton Internet Security, it should include both the Norton Firewall and Norton Antivirus. All of the setup and management is done in Norton, preferably during installation although you should be able to access the programs to make adjustments after installing. Once the installation is in place, you shouldn't have to go to Control Panel for AV or Firewall management, since it's all turned over to Norton.
Some people don't have problems leaving both the Norton and WinXP firewalls turned on at the same time, but it's possible to get conflicts, so turning off the built-in Windows (WinXP) firewall is recommended - even by Microsoft - when you have another firewall on the same machine. Your installation of Norton Internet Security should already have done this for you, which would explain why you don't see anything in the Control Panel/Security Panel to adjust.
I don't have a recent copy of Norton Firewall to refer to, but generally Norton places an icon in the System Tray at the bottom right of your monitor screen. (It usually looks like a tiny computer with a yellow screen.) If you double click on the icon, it should open the Norton manager, and it's usually pretty good about telling you what's properly set and what needs attention. With the Internet Security package, I would expect all the adjustments you can make to be there, for both AV and Firewall.
In some older versions, or if you installed the firewall separately, you might find the Firewall stuff in a separate control panel that you would probably find in a folder labelled either "Norton" or "Symantec."
I suspect that the reason you're not finding any settings in Control Panel is that Norton does it all, and the user adjustable security settings in Control Panel are turned off to avoid conflicts.