try this free program.
Download inSSIDer and Discover the Wi-Fi Networks Around You | MetaGeek
it will show you what channels are being used in your neighbourhood, and so you will know which channels to avoid.
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*edit*
ah sorry, reading your post, you say you can't use a scanner as you don't run windows - is that correct?
oh well, i'll leave this post as it is as it may help others.
maybe you can persuade a friend to come over with a laptop to scan for you?
or if you have an android phone,
wifi analyser does a similar job.