Disable the wireless first.
Then make sure you are using DHCP (Automatically Receive an IP Address) Then do the following:
Go to Start > Run and type in
then type in the command window
and look for the IP ADDRESS line. It should start 192.168 - if it starts 169.xx.xx.xx then theres possibly a problem with your ethernet cable, and try a different one.
Feel free to copy/paste the command window results for further diags.