Switching between LAN and modem access - how?

This may be obvious, but after fiddling around for a while I can't seem to find out how to do it - on Linux, I've always used one or the other. I have a PC with a network card, and a modem. The card is set up to use the gateway for net access, and the modem can dial out directly. I can access the net with the modem fine, but I also want to be able to use the LAN when I feel like it, just to be awkward. However, I can't seem to get the LAN connection working. On Windows, in IE -> Tools -> Connections, you can just tick Never dial out, and it then uses the network until you want to use the modem again. Is there anything similar in SuSE? Thanks Kevin