If you want to get real elaborate you can put the AP outside your firewall and use something like VPN or Radius authentication to get in but for the average Joe, if you use WEP (changing your keys frequently and using a difficult passphrase), MAC filtering, turn your SSID off, turn off DHCP and change the default subnet, then use Access Lists if your AP supports it, your pretty safe. I wouldn't put my credit card numbers on my PC or anything but it is not something a casual wardriver would bother with, much less be able to get into in a reasonable amount of time. If you don't hammer your network non-stop then they can pretty much forget it. I'd think you'd notice a car camped out at your house for a day or two. Clearly, 802.11 security measures are not enterprise ready, well not affordably anyway, but for the home user, given the proper attention, there should be very little concern about the data on your rigs.