The first question is whether your Internet Service Provider (ISP) has given you real IP addresses for your computers or whether you connect through something like an online service where you get only one IP address.
In the former case all you need may be RRAS, free from Microsoft.
In the latter case the second question is whether this one IP address is constant or whether you get a different one, dynamically, each time you dial up, like with most online services.
Third question is whether the Windows 2000 machine runs Professional or Server. Server has NAT built in.
Fourth question is whether you want control over what the clients do, which would require a proxy server, or whether you want them to be able to do anything on the Internet, which would favor a Network Address Translator (NAT) solution.
Finally, Windows 98 SE, Windows ME, and Windows 2000 contain Internet Connection Sharing (ICS). If your Internet connection can be put on a machine running one of these operating systems, you may not have to use additional software.
For the following Microsoft Knowledgebase articles you can search: http://support.microsoft.com/support/search/c.asp?PSL=1 using the Q number.
Or you can insert the six digits of the Q number in place of the six zeros in the following URL and go to the Knowledge Base article directly: http://support.microsoft.com/kb/000000/
For more information about ICS, view the article in the Microsoft Knowledge Base:
Q234815 Description of Internet Connection Sharing
For information about troubleshooting ICS issues, please view the article in the Microsoft Knowledge Base:
Q238135 How to Troubleshoot Internet Connection Sharing Problems
For information about troubleshooting automatic dialing using ICS, please view the article in the Microsoft Knowledge Base:
Q236445 ICS Does Not Automatically Dial an Internet Connection
For information about disabling Internet Connection Sharing, please view the article in the Microsoft Knowledge Base:
Q230112 How to Disable Internet Connection Sharing
For information about your computer restarting before the ICS Wizard finishes, or for information about uninstalling and reinstalling ICS, please view the article in the Microsoft Knowledge Base:
Q227172 Your Computer Restarts Before ICS Wizard Is Set Up Completely
For information about problems setting up ICS, please view the article in the Microsoft Knowledge Base:
Q229829 Internet Connection Sharing Is Not Set Up Correctly
For information about ICS and the TCP/IP requirement, please view the article in the Microsoft Knowledge Base:
Q230070 TCP/IP Must Be Bound to All Adapters Connecting ICS Host to LAN
NAT is simple to install and use but doesn't offer all firewall security features. It simply routes everything through and out into the Internet.
Proxy servers allow you to set up protocol paths, so you can control what is routed. They also allow you to limit incoming connections to certain types. Examples are Microsoft's own Proxy Server and WinGate.
Sygate NAT: http://www.sygate.com/
Wingate: http://www.wingate.com/
Nat32: http://www.nat32.com/
WINRoute: http://www.winroute.com/
NetProxy: http://www.grok.co.uk/netproxy/
WinProxy: http://www.WinProxy.com/
MS Proxy Server: http://www.microsoft.com/
PPPShare: http://www.pppindia.com/intl/pppshar/
Sambar Server: http://www.sambar.com/
VSocks Light: http://www.pscs.co.uk/software/vsockslight.html