Tech help motorola sbg901 wont work with ethernet connection on computer

Hello,
I purchased the SBG901 and tried to connect it to my desktop throught he ethernet connection. It will not load and says that my card is not configured correctly. My laptop which I am using now is working wirelessly but the hard cable to my desktop is not. It worked perfectly with the motorola surfboard modem that I was renting from comcast and the new one is working with comcast as I can surf wirelessly. My desktop doesn't have wireless. Anyone have any suggestions? Comcast and motorola were no help.