Wiimote makes an aweful light gun, wii or PC with BT dongle you won't get the same thing as a real light gun.
The light gun makes that you know where you shoot, that's what is computed.
The wiimote doesn't. It "moves" just like a mouse, but with different interface.
If you'd play gun games with a joystick or a trackball, then the wiimote might be satisfactory, otherwise its a disapointment waiting to happen.
unless of course there's a "good way" of calibrating it?