With Norton, you must remove using Add\remove programs.. everything related to Norton, including all the stuff that states Symantec..
Next go into Documents and Settings\<user name> and Documents and Settings\All Users and look for a folder called Symantec and delete it.
Next go to Program Files and remove the Symantec folder.
Next go into Program Files\Common Settings and remove the Symantec folder,
Next run Regedit and use the Menu, Tools Find option and search for Norton and Symantec through the entire registry and delete all folders / keys...
Then if you have a registry cleaner, run it,
then install your new firewall / AV.
I would however suggest Panda Platinum Internet Securities 2005.. it contains a software firewall that is easy to configure.. basically after you do a complete install, you can just launch SFC OP, and get to the Single Player/ Multiplayer screen.. hit the windows key and wait for the panda pop up next to the task bar clock.. click Enable or allow.. next go back into game and click the Multi-player tab and hit Dynaverse, then hit Accept, then windows key, then Panda will ask for permission again.. click Always allow..
Exit SFC OP, launch GSA and do the same thing with Panda.. This will allow GSA to work without incident and it will allow SFC OP to work without incident online or in LAN.. do this with each of your programs that need web access .. wha-la.. no ports to configure.. Panda will handle it on a program by program basis automatically.. Panda blocks file connections independantly.. as such, SFC OP in Panda will have access to all ports on your system, but no other program until you give it permission.. as such someone trying to access your system from the outside, Panda will notify you as it is not coming in on any of your running programs and panda will automatically keep them blocked until you tell panda to allow.. and even then Panda offers options of Deny this time only, Always Deny, Always Allow, Allow this time only and close (basicallly Deny this time only)... It also scans for spyware and unknown incoming threats that are not known viruses, active script blocking and invalid JS blocking and many other things... plus Panda updates 5 or 6 times a day for new virus signatures, usually pulling 2 or 3 during the check, then it gets the master file for all non urgent spyware\viruses at midnight each night which usually has about 200+ definitions...
Anyhow, it is the best software firewall and AV I have ever used.. it even notifies when someone tries to enter a backdoor on to your system.. Hyuristics enabled AV will also notify you of unknown files which it will quarentine automatically.. as such, you can go to the quarantine section and right click on the file (if your programs needs it) and select Restore, then Panda will ask how you want to restore.. Disinfect and restore or just plain restore... So far the only file Hyuristics finds on my system as unknown is the Windows Media Player 10 launch file, which should be updated by Panda in just a few days or maybe a couple weeks..
Hope that this helps.