Brian,
There are two very basic things you can do to "SECURE" your wireless network:
1) Encryption - your basic WPA should serve you fine when coupled with
2) Wireless MAC filter - This feature means only PRE-DEFINED MAC ADDRESSES/Computers are allowed on the network.
It will also help if you run your wireless network in STEALTH mode by setting Wireless SSID Broadcast to DISABALED.
Of course none of this means anything if your router password is still "ADMIN"
