Most wireless routers offer MAC address filtering. This is the only security method I've used and it's near impossible to defeat.

Every network connection device, whether it's a USB Wireless connection, built-in wireless, or built-in hardwired LAN port, has a MAC Address. This is a unique code that identifies that specific piece of hardware. If you buy 2 of the same device, each will have a different MAC address.

Just log in to your wireless router (be sure to change the SSID name and most importantly - CHANGE THE PASSWORD), and enable MAC Address filtering. Enter the MAC Address of each device and assign each a name. (The name does not have to match the name you originally assigned the computer.) Be sure to apply or save changes and reboot your router.

To get the MAC address for your network device:

1. In Windows, click "Start", then "Run".
2. Type in cmd , and hit Enter
A black window (DOS box or command prompt) will appear.
3. Type in ipconfig /all (note: there is a space before the slash, but not after)
4. Scroll through the info that appears. You will have one or more entries titled "Ethernet adapter Local Area Connection". There might be a number at the end.
Three lines down will be the "Physical Address". That is the MAC Address. Typically, when you enter it in your router's filter tool, you won't type the dashes or colons.

I even have my router's SSID (name) set to broadcast for maximum compatibility. It's never been hacked, even though I suspect the kids in both houses next door have tried.