You should set the Linksys address in accordance with its user guide. I'd think this would be something more like 192.168.0.200 or 192.168.0.100 or 192.168.0.254. You also need to use DHCP which you didn't mention. You also didn't mention channels, but normally you'd want the two routers to be on different channels so that they don't conflict with each other. You didn't mention that either.
i just apply for timewarner cable service and got this motorola sbg6580 wireless modem, but i have really weak signal on second floor, only 1 bar for my ipad. when i google online found that i can use my old linksys wrt54gs as an extender, i gave it some setting.
first i upload the dd-wrt file i downloaded. and below is my setting for linksys:
local ip: 192.168.0.2
subnet mask: 255.255.255.0
wireless mode: client bridge
wireless network mode: mix
ssid: (same as motorola modem)
network config: bridged
wireless security mode: wpa2 personal
WPA Algorithms: aes
WPA Shared Key: ( same as motorola)
am i setting these correctly? my motorola lan ip is 192.168.0.1