Cannot connect to internet via wired adapter
I'm using Debian right now and I have a wired network adapter and a wireless one all pluggging into PCMCIA (it's a laptop). At the moment, I figure the wired one is easier to set up, so I plug it in and the eth0 shows up with no internal ip. So, I type in "ifconfig eth0 up 192.168.1.102", and once that's set, I am able to ping my router. Now, I still can't use the browser, as it says the host isn't available and I can't ping anything outside of the network. How do I fix this? And also, is there a way to set it up so I don't have to set the IP everytime I change networks? Any help is appreciated...
I also don't seem to have an /etc/resolv.conf.