Much easier would be to enable MAC address filtering. Each computer has it's own unique mac address. You can find it by running IPCONFIG from the command line. You'll want the mac address that is bound to your wireless card. You'll need this from each computer on your network. Depending upon they type of router you have and its firmware, they may show you connected the mac addressesfrom each computer (D-Link 614+ does). Then you simply allow only those mac adresses to access the network.
WEP or Wired Equivelent Protocal is really and after thought added because of the vulnerability of Wi-Fi.
This is enabled by entering a hex key of a certain length depending on the level of encryption desired. Stronger encryption equals longer key. I don't remember off the top of my head all the key lengths but I do know, that a 64 bit key is 10 characters. You enter them into the routers firmware and then CAREFULLY write the number down and enter it into your individual computers wireless applets. Be carefully entering the characters because if one digit is off you will not have access and could end up re-entering the numbers again. If your routers firmware will allow you to copy and paste the WEP key from the entry field, then copy it and email it to all the computers, then you can copy and paste it into each computers WiFI applet. 64 bit isn't too bad but copying a 128 bit key character for character can be a real pain.
You can also enable Mac filitering for LAN access so someone could'nt tunnel through your routers firewall and access computers on your wired LAN. This should provide enough security to keep out all but the most skillful hAX0r5.