"It was related to the router drivers/firmware installed machines simply not working with the cisco but different modems working fine with those routers."
Oh rly? Funny story, I was once a Moderator/Power user on Dlink's forums. Do you mean the issue with the DCM-202? Not that it matters, since you have a valid question either way, just curious.
On thing that will help is inSSIDer, which is a free wifi scanning tool. Be warned, looks like the makers have released the new version as pay only, and made the free version a demo only. You can still find the free version, but I don't want to be posting non official links.
They also have different tools/Apps you can use on your smart phone. While it won't show inference, it does show you other networks which might be intereing. Also, since the signal meter is more sensitive then the little Wifi signal strength thing, you can use it by moving the laptop around like you were dowsing for water. It might lead you to the cause.