Duplexing

You can check and change the settings in your network card's advanced options.

This should be set to the preferred option by default.

Start->Settings->Control Panel->Network and Dial-up Connections. Choose Local area connection. When the Local Area Connection Status box appears, click on the Properties box. You should see the network adapter that you are using in the Conntect using field. Choose Configure. Under the Advance Tab of the Network Card Properties box, you should see Link Speed and/or Duplex listed. These properties may also appear in a field called Media Type or something to that effect.

Hope that helps.