IMO, the hardware switch is the "master" switch that overrides any software switch, even BIOS Wi-Fi enable/disable. If the hardware switch is off, no Wi-Fi will be enabled even if the BIOS is configured to enable Wi-Fi use. The best software Wi-Fi switch that I could think of without installing 3rd party software is to use Windows Mobility Center. To invoke it, press the Windows Button and X at the same time while in desktop mode. You should see something like this:
