New uverse arris router/modem

My speed stream 5100 started quoting on me, so had att send me a new arris router/modem thinking it would provide better wifi coverage throughout the house, when I'm really not thinking it will do this. (No antennas on this unit). Current setup is the failing seimen 5100 speed stream with cycsco wrt54g. Any advice? Really just needed to replace the modem and keep using all as I have it. Maybe the arris will work out ok, bit I doubt the range will be sufficient. I have 30 days to return it and can't try it until tomorrow night, at which my service will be turned over to the new uverse stuff. We rely on the wifi for our cell phones so I gotta figure this out quick. I don't even see a way to use my cysco extender with this arris unit. Damn, should have ckd this out more before pulling the trigger. However att told me I'd have to use this newer unit. My kids bedrooms are a ways away from the location of PC where router sits and I need that range of wifi to make it to them.

It looks as if I must use their modem/router, but I should be able to bridge my cysco router to this att unit, correct? And I should still be able to connect my 2 tvs using my current cat5 cables, into the cysco? I just wanna bypass the att arris router altogether and just use its modem. Thinking the cysco unit better for wifi with its antenas. Gosh what a mess!