A topic I haven't visited in a while...

I used to harp on securing wireless networks and listed 5 simple things you could to to secure yours:

1. Change the default SSID and Administrator Password
   
2. Enable MAC address filtration to only allow PCs you know to connect
   
3. Limit DHCP to the number of addresses you need so that you will have IP conflicts if someone gains unathorized access
   
4. Disable SSID broadcast if your router supports it
   
5. Install a personal firewall on each of your computers - this will not only help if your home network is compromised, but also protect you when you use public hotspots.
   
   

In any case, netgear has a similar document on their web site. Needless to say, it contains a lot of advice specifically about their products, but it is great generic Wi-Fi security info.