It's actually quite easy. The main thing is to make sure that Internet Connection Sharing service is set to automatic in your services.
Start menu->Settings->Control Panel->Administrative Tools->Services
Right click on Internet Connection Sharing->properties->startup type->automatic Apply
You must have two nics installed in your main W2K computer.
Right click on "My Network places"->properties->
Right click properties on MAin internet NIC and click on "Internet connection sharing" under the Sharing tab. This will set your other nic to a predifined internal IP addy. No further adjustments need to be made on your internal nic.
Then you just make sure your second computers nic is set to automatically retrieve its settings from the w2k machine.
Further details can be found here...
http://www.elementkjournals.com/ntp/9912/ntp99c1.htm
Good luck.
WwWonka
AOL IM: wonkamax