Hi for a laptop you should look at /etc/pcmcia/network.options (not sure if that path is 100%)
this, if configured properly, will automaticly bring up the interface with the proper settings when the card is inserted. you can also do tricks like have different ip,dns,etc for different cards, my laptop uses this as I have wireless at work and wired at home, you probably won't need anything that fancy. I'd provide more specifics on the file format, but my laptop is in my office and turned off, while I at home. It's pretty straight forward and well commented, if you know how to use ifconfig, you should have no problems. -Jon