Hello all, Back in the US after 3 years in Australia and am now back to buying/upgrading my tech. After years of "renting" a modem, I'm done with that. I'm gonna buy one but wondering if the modem is best matched to whoever my ISP is or is it best matched to the Airport Extreme? Aren't they just basic switches (layman's terms) and are all pretty much the same? I'm just not sure if Comcast, AT&T really has a device that is really propriety to there system of if its just a box. Does that make sense? Thx for your input!