Hi, have you checked to see if the Internet Protocol TCP/IP is installed on the Windows 2000 machine? Go into Network Connections, right click on the connection and select Properties. On the General Tab is a list of all connection and file sharing protocols installed on the system. If it has a check mark in the box in front of the label, then it is installed, if no check mark is there, or it is not listed at all then it is not installed and you will need to do so. It is simple, just place a check mark, then click Install, and follow the onscreen instuctions if any appear. You also need to ensure that "Client for Microsoft Networks" is installed, and if you want sharing enabled you also need, "File and Printer Sharing for Microsoft Networks and the "QoS Packet Schedular" service.
Now, you may also be having a problem with the DHCP, if the 2000 machine is not getting an IP Address it is impossible to connect it to anything.
Try this Microsoft website and see if it has anything which will help you solve your issues. It also has links to other resources:
http://www.microsoft.com/windowsxp/using/networking/maintain/troubleshoot.mspx
Here is another website which may be usefull to you as well, at least it was to me when I first started with networks:
http://www.pcstats.com/articleview.cfm?articleid=1427&page=1
These will get you off to a good start, good luck and have a great day!