The BBC released a great article related to wireless security ('How to keep your wi-fi network safe' -  27/04/2007).

The bottom line of this article is that wireless home networks carry a security risk if not adequately  secured. The goalpost with security is always moving. What was perfectly save last month might become a risk tomorrow.

It seems very plausible that a unsecured WiFi might get abused - everybody will probably go along with that statement. A network however is not 'secure' anymore if a hack has been published. This is now the case with the WEP encryption method. WEP is used to secure many wireless routers.

I suggest to check your routers' configuration and switch to WPA if you can. Your WiFi can only be abused about 200m around your house - which limits the risk. It feels much better to not leave a window half open. 

Switch off your wireless component if you have a router with wireless but you are only linked through a network cable.