Windows XP Internet Connection Sharing(ICS) automatically configures internal clients so that they can access the Internet by using ICS. You could want to configure a host and not let it to be configured automatically.

To configure a static client on ICS you should follow the following steps:

-Add a valid ICS private IP address to your client.
-Configure the default gateway.
-Configure the preferred DNS server.
-Add MSHOME.NET.
-Add an entry for the client.

The rest of the article you can find it on Microsoft's page.