I recently went though the same thing (w/SuSE9). I'm configured to a Linksys router (WRT54G) that's connected to my DSL modem. I get my IP via DHCP from the router. Here's a summary of my steps:
*Configure the network card (either through Yast or from KInternet)
Assuming you're connected to the router by hardwire (ethernet cable and not trying to go wireless) and that the router is providing the IP address (via DHCP),
set the card to "Setup Auto...(via DHCP)"
set the default gateway to the ip address of you router
(Linksys default is 192.168.1.1)
*configure the DSL device (either through Yast or from KInternet)
Chose provider name (if listed) or use custom and name it SBC
Use the Name Servers provided by SBC, which you can get from the details of your SBC account(this is the also called the DNS).
This is the basics. You may have to do some trial and error. In a nutshell, you want the OS to talk to the modem via the network card. You have to set up both.
I'm more familiar with Windows and just learning Linux. The second step is what confused me because I'm not used to configuring a modem (and haven't since I left dial-up). Apparently, you have to configure it like the old DOS/Windows dial-up set-up. It's a learning experience, but you're in good hand in this group. They've help me alot.