go Start then Run in XP - (Windows key plus R in Vista and Windows 7), then type in the following, including all the spaces:- cmd /k ipconfig /all -- then press Enter and from the black form that shows up, take a note of the numeric code beside the word "gateway" -- usually something like 192.168.1.1. Type exit to close the black form.
Disconnect the Linksys from the 2Wire and connect a computer via network cable to the Linksys.
log into your Linksys setup your wireless security using a different SSID, I recommend also to use WPA2 mode instate WEP.
Then disable DHCP and change the LAN IP to Gateway IP but ending in 253. If gateway is 192.168.1.1, set Linksys to 126.96.36.199
then connect the Linksys using one of the four LAN port to the 2Wire.
try to connect your Mac to the new SSID