Re-Installing and/or Re-Registering My AirPort Express

Question

I purchased an AirPort Express when I purchased my computer (in June 2004).
Unfortunately, when I took my computer to college, they would not allow me to use it in my dorm.
Now that I no longer live in the dorms, I want to use my AirPort again. I plugged my high-speed internet cable into it and it seems to work (because the light is green); however, I do not know how to create my own network so that others cannot "steal" my internet.
I think my computer does not recognize my AirPort Express anymore; furthermore, I do not have the software that came with it to re-install and/or re-register it again on my computer (I cannot find any files that have "AirPort Express" when conducting a search on my computer).
What do I do?
iBook G4   Mac OS X (10.3.9)  

Answer 1

Reset and then reconfigure from scratch
Resetting AirPort Express
http://docs.info.apple.com/article.html?artnum=108044
Applications > Utilities > Airport Setup Assistant
or
Applications > Utilities > Airport Admin Utility
Applications > Utilities > Airport Admin Utility
Scan and Select your Airport
On the Airport Tab
Change Wireless Security
Use WPA Personal
Use a password like this:
4fghj8eybs9nf78swnu
Remember to write it down.
I would also change the Wireless Network Name as well, but this is not needed.
Click OK
Click Update
You will now be thrown off the wireless network.
Wait at least five minutes.
The from the Airport icon in the menu bar, select your network, you will be asked for your password, enter the password, check keep in Keychain (so your Mac will remember it).
That's it.
Don't worry about using anything else, WPA is pretty much uncrackable unless you use a dictionary word for a password such as "table".