Finding a free wireless channel

Most of my neighbours are blasting out wireless networks that I can pick up in my home. But how can I ensure I get the best performance from my own network?  Simply put I need to choose a different channel. But how can I find out what channels are in use?

netsh wlan show networks mode=bssid

Find a free one (in my case anything but channel 11) and set the access point to it. Simple!