Hi,
I believe you are talking about SEP 12.1.
SEP 12.1 is not supported with windows 2000.
System requirements for SEP 12.1
http://www.symantec.com/docs/TECH163806
You can install SEP 11.x agent on windows 2000 machine.
You can manage SEP 11.x agent from SEP 12.1 SEPM