Another thing that you can do is to set up a MAC address list on your router. Every wireless adapter comes with a unique MAC address, and listing them in the router allows only those specific devices to connect. That will make it more complicated to hack and thus slightly improve your security.

In general, I would strongly recommend against using WEP for any reason because somebody could connect through your internet connection and do illegal activities - and it would appear that YOU did it. Even somebody parked on the side of the road could do that.