If you enable WPA and hide the router's (Hub's) SSID, this will prevent "uninvited guests" from connecting to your wireless network. This has no effect on your "wired" ethernet connection to the PC which is already a secure connection.
I'm not familiar with BT's Hubs, but routers generally also have the option to enable "MAC Address" filtering so that only those network adapters whose MAC addresses have been entered in the router's settings can connect.
To find the MAC address (Media Access Control address) of your network adapter, open a Command Prompt window and run:
then look for the "Physical address", which will be a string of twelve hexadecimal characters in six groups of two.