LAN website and internet

I am developing a network of 20 computers with windows2000server on server side and win2000prof at client side. I want to host a website on intranet so i have installed IIS. On the other hand i want to proved the network gain to network through the same server. How can i do it?Suppose the web site on intranet is www.abcd.com. How should i manage the network so that when some one types www.abcd.com he is not to hit the default gate way.