ok, so I've still not gotten a clear picture. You have a surfboard 5100...single ethernet jack, right?

And you have 2 WRT54G devices. Where's this 'router' you mention? And is it really a switch? There is no reason this shouldn't work, if you set it up right.

Some questions:
1. How many IP's will your ISP allow you to have? Often it's only 1, but could be more.
2. How are you actually, *PHYSICALLY* connecting these devices. I don't care about channels, ssid's, wep/wpa/ROT13, I wanna know WHICH CABLE goes WHERE.
3. What is your final intent?