Click on the start knob. Right click on computer in the left column. Select manage from the pop up list. Click on device manager on the left of the Computer management snapin. Is your network card listed under the Network Adapters? If it's not then you have a driver issue or it's disabled in the BIOS.
If it's listed there then click the start knob and right click on Network. Select Properties from drop down list. Click manage network connections on the left hand side of the Network and Sharing Center snap in. If your network connection is listed but is greyed out then right click on it and select enable.
Otherwise your problem is beyond the scope of this cup of coffee and you need to give us more details.
