In Windows XP Professional?

Note: the following is untested.

1. From the Start menu, select Settings, then Network Connections.
2. If Local Area Connection is not an option, select Create a new connection from Network Tasks.
3. Click Next to continue. Check the Set up a home or small office network radio button. Click Next and then Finish and then Cancel.
4. Select Local Area Connection.
5. Click on Internet Protocol (TCP/IP) and then Properties.
6. Under the general tab, make sure Obtain an IP address automatically and Obtain DNS server address automatically are set.
7. Click OK twice to close the windows.