Upgrade to N?
To change the channel, log onto the router and hunt for the channel setting. To log onto your router, find its IP by opening a command prompt and typing ipconfig. Where it says 'default gateway' that'll be your router's IP, probably 192.168.1.1 or 192.168.2.1 or maybe 192.168.1.100.
So type in http://192.168.1.1 into your web browser, then when it asks you to log in it'll be something like username admin password admin or blank password.
My Belkin N router is 192.168.2.1 and username=admin password=blank
When you get to the config screen you'll see a page marked 'wireless' or some such, then you'll be able to change the channel. You might also need to change the channel on your computer if it's not automatic… try windows help for that – but before you start messing with it as you'll lose your connection 🙂