Is there a simple way of checking whether your wireless network is being used by unauthorised users? I am using WPA security with an alpha numerical password mixed with upper and lower case also my SSID is hidden so I think it should be fine?
Also make sure your router's password (not the wireless password, the password used with probably 'admin' as the default name when logging into the router pages), is also different and alphanumerical and mixed case. Ideally over 10 characters too.
Also, in your router's pages should be a page with the MAC addresses of the computers using the router. This will show anyone else linked, but given your security setup you should only have your own computers.
The MAC addresses will show anyone currently connected. On the router I've actually checked (my old Belkin), there was no logs facility. I have a Netgear now, but have never looked for any logging information.