As far as I'm aware, Sky don't provide modems, just Netgear routers. They have their own firmware installed and they won't give you the settings to use a different one.
Going back to the original problem, have you tried changing the channel the wireless is broadcast on? Is it sited near a body of water, eg fishtank, radiator?
-------------------- OK OK I can't go any faster! aaaaaaaaaaaagh!