Ref:
http://www.speedguide.net/faq_in_q.php?qid=346
Under Windows Vista/7/2008, the default GUI wireless network list does not display the channels access points use. To find the channels, you have to do the following:
1. Navigate to Start > Run, type: cmd to enter command prompt
2. Type:
netsh wlan show all
2a. Alternatively, type:
netsh wlan show networks mode=bssid
This will display a list of all wireless networks in range, along with the network channel, signal strength, and security type used.
Ideally, you should pick a channel that is at least 3 channels apart from those used by other networks in the area.