WPA2 Personal lSecurity and a non-dictionary password are your best defense.
Don't bother with "closed networks' or things like that. There are dozens of free utilities on the Internet that will reveal a closed network in seconds.
If you want to change the wireless network name and/or password, here is how to do this:
Open AirPort Utility - Click Manual Setup
Click the Wireless tab located just below the row of icons
Edit the Wireless Network Name as you wish
Edit the Wireless Password as you wish and Confirm
Click Update to save your changes
Your AirPort Extreme provides an excellent NAT firewall for your network. There is really no need to enable the firewall on your computer if you are connected to the AirPort Extreme.
Excellent and thanks for the very prompt reply!
Is the WPA2 Personal ISecurity default when the Extreme is configured? Or do I need to turn that feature on? I know I have a WPA2 password, so assume that is for the WPA2 Personal ISecurity? I'm probably just getting terminology confused.
Sorry for the dumb questions. It's probably pretty obvious I'm a computer newbie...