Router on an ATT DSL line and mixed XP & Win 7 Computers on wireless network

[J in Chicago]

Downgrading Netbook to XP for testing reasons, Installing new router and Wireless lap top for a friend. IMPORTANT if you know how to un-install the AT&T modem software that they have you load on activation I'd like your help. I had new network and New WIN 7 laptop working fine. As soon as I plugged in older XP tower into router lost all Internet connection ability. Router comes with free Network Magic from Cisco which I like and think it will make sharing across XP to Win 7 easier. Any help is appreciated. Talked XP user into uninstalling McAfee fire wall  now to prove it it is ATT software expecting modem as first connection not router.
Thanks AE for being here.

[Carolina Mike]

J,
You should not have to uninstall that software.  Try this:
1. Unplug Modem totally( no Power) 2 minutes
2. Unplug Router totally (no Power) 2 minutes
3. Make sure computer is off
4. Plug in Modem
5. After modem is fully up cut on router
6. After router comes up fully cut on the XP Tower only and see if it connects
7.  If it does then turn on the Win 7 Laptop.  You should be good to go

[J in Chicago]

Thanks will give it a try.

[J in Chicago]

They were unable to get it to work with tower only. Told the to spend $30.00 more for AT&T router and they would have AT&T support for their DSL, Modem, Router and any required software.