The driver for the network card might not be installed. To check, right-click on My Computer and select the hardware tab. Then click on device manager. If your network card does have a driver installed it will show up under Network Adapter. If any drivers are not installed, there will be question marks by the devices that don't have drivers installed. If you end up needing any drivers, they should be on one of the cds that came with the computer or on the computer manufacturer's website.