1) Go to 192.168.1.1 to access your Linksys's admin pages.

2) In SETUP tab, change the "Domain Name" to "@attbi.com" (may not be necessary, but it beats having "@home" there)

3)Select "Obtain an IP Address Automatically." Depending on your firmware version, you may be prompted that your connection will be reset when you press "Apply."

4) Set all three DNS servers to 0.0.0.0 so that they are dynamically set when the router gets it's info from the cable modem. I've seen some cases where even with the dynamic IP address assignment, the DNS assignment remains static.

5) Hit "Apply."

6) When the settings are saved and you are prompted to continue, press the "CONTINUE" button.

7) Go to the "STATUS" tab at the top of the page. Check the WAN portion (not the LAN portion) to make sure you have an IP address and Default Gateway other than 0.0.0.0. If so, then you are golden.

8) CLOSE ALL BROWSERS to reset your browser cache. I've seen a lot of people complaining about only being able to access the AT&T switchover pages - even after making changes. It's your browser cache. Trust me - it happened with me.

9) If you have your Linksys router running DCHP and issuing your client addresses on your home network, renew the DHCP leases on ALL your client machines. You can either reboot, or do it this way, depending on your OS:

Windows 9x: Start, Run, type "winipcfg" then press ENTER, then press the "Renew All" button.

Windows 2000: Start, Run, type "command" then press ENTER, then type "ipconfig /renew" and press ENTER.

10) If you have a Static 192.168.x.x IP address on your machine, make sure your static DNS server settings are set to your router's IP (192.168.1.1) so that it will get the new DNS server addresses.

11) Surf like a mad man!
(thanks to sjjenkins)