clustering terminal server

We are currently have a Windows 2000 server running terminal services for about 20 users. We will be adding an aditional 50+ users in the near future. We realize that we will need an additional server to handle this load and intend on purchasing an additional server. The thought is to cluster these two servers as a way of balancing the loads. How is this set up on the network, are there any additional settings that need to be modified on the LAN? What are some pros and cons of doing this? Do you know of any helpful links?