Have you checked wifi signals as to their effectiveness?
Is your wifi router/ access point using good encryption technology?
Wardriving: Peter Shipley coined the term "wardriving" the practice of deliberately searching a local area looking for wifi networking signals.
You do know that some wifi(WEP) encryption is easier to hack and break into than others(WPA2)
There are also other ways that people attack you and your information and resources.
Hackers use fake wifi access points to steal peoples logins. be careful where you accept a wifi connection, as unencrypted wifi can be very dangerous, at lest assume that all your network traffic can be stolen and analyzed. I.e. do not enter userids and passwords on unencrypted wifi connections.
we can help you test and audit your wifi, including for PCI auditing purposes (has to be done quarterly