I'm running an Exchange 2000 Server machine. Can I add another Exchange server and set up a cluster?
You can't integrate an existing server into a cluster directly. When you install Exchange 2000 on a Windows 2000 Advanced Server or Win2K Datacenter Server that's part of a cluster, Exchange Setup installs the necessary resource DLLs and management pieces to let Exchange function in the cluster. However, you can't turn an already-installed Exchange server into a cluster member after the fact.
Fortunately, you can achieve the same result another way. Install Win2K AS on the server you were going to add anyway, and turn it into a one-node cluster. Install Exchange 2000 on it (putting it into the same administrative and routing group as the existing server). Move all mailboxes, public folders, and connectors to the new server, in the same way you would if you were going to permanently decommission the original server. Then, reinstall the Windows OS on the original machine, but this time, join it to the existing cluster as a second node. For this configuration to work, you must buy and configure appropriate shared-storage resources, and all your hardware has to be on the Windows clustering Hardware Compatibility List (HCL). The Microsoft article "Microsoft Cluster Server Hardware Compatibility List and Testing" (http://support.microsoft.com/default.aspx?scid=kb;en-us;q22497) provides background information and resources for determining acceptable hardware.