You can install a stripped-down version of DD-WRT on that WRT54G2. That would make it a far more robust router than the SMC. Use the SMC as a modem, and the WRT54G2 (with DD-WRT) as a wireless router.
EDIT: A couple posts I've read suggest that the SMC modem can NOT be switched into bridge mode. If that's the case, then your options are limited. Put DD-WRT on the Linksys, disable its DHCP, and use it as an AP.
bent and Inga Premium join:2004-10-04 Loveland, CO
When I get some down time I'll check it out for sure, but I'm pretty sure when I turned DHCP off on the SMC that it was handing out the public IP. -- Greedy Old Pigs v. The Donkey Show