what you are trying to do is called ICS or Internet connection sharing. plug the ethernet into the laptop and then into the desktop. from there go to your wireless card on your laptop. with XP go to network properties or with vista/7 go to network and sharing center then clicking on change adapter settings. double click on your wifi card connection and go to properties, then go to sharing, check the box that says share and hit ok. this will change the ip address on your Ethernet port and it will come up. under this same sharing tab you can go to settings and add ports if you need to port forward.