click on your xp start menu go to run and type devmgmt.msc
when you get the device manager open, check under network adapters and make sure your NIC is recognized in the system and installed properly (it will NOT have a red question mark or yellow exclamation mark if it's installed properly)
if it's ok in there, then follow these next steps, and let us know what happens.
- Using the ping command to test the connection between your computer and the router or gateway
- Using the ping command to verify your Internet connection