if i ve understood correctly:
you have many servers who are member of the same domain and you want to access them remotely from windows xp/vista clients for administrations. additionally you would have more than two administrators logged on to these servers concurrently.
assuming the above, i suggest:
1. install terminal server in application mode on all the servers you want to access remotely. the detailed help is available at
http://www.microsoft.com/windowsserver2003/techinfo/overview/quickstart.mspxit is pretty straight forward like installing any other windows component.
2. install license server on any single server and make all license server access it for licensing information. the procedure is also given above.
3. i suggest you buy user CALs based on the number of users you have.
revert back in case of any problem