To enable Internet Connection Sharing on a network connection

You must be logged on to your computer with an owner account in order to complete this procedure.
Open Network Connections. (Click Start, click Control Panel, and then double–click Network Connections.)

Click the dial–up, local area network, PPPoE, or VPN connection you want to share, and then, under Network Tasks, click Change settings of this connection.

On the Advanced tab, select the Allow other network users to connect through this computer's Internet connection check box.
If you want this connection to dial automatically when another computer on your home or small office network attempts to access external resources, select the Establish a dial–up connection whenever a computer on my network attempts to access the Internet check box.

If you want other network users to enable or disable the shared Internet connection, select the Allow other network users to control or disable the shared Internet connection check box.

Under Internet Connection Sharing, in Home networking connection, select any adapter that connects the computer sharing its Internet connection to the other computers on your network. The Home networking connection is only present when two or more network adapters are installed on the computer.

To configure Internet options on your client computers for Internet Connection Sharing

Open Internet Explorer. Click Start, point to All Programs, and then click Internet Explorer.)

On the Tools menu, click Internet Options.

On the Connections tab, click Never dial a connection, and then click LAN Settings.

In Automatic configuration, clear the Automatically detect settings and Use automatic configuration script check boxes.

In Proxy Server, clear the Use a proxy server check box