exchange standard n enterprise together

Hi

Is it possible to have microsoft exchange 2000 standard and enterprise working together. Somebody told me that could not be together in the Active directory. I know that they are both smtp server, so there is always a way to transfer message between them, but my question is if they can be both installed (in different servers of course) so i can manage both of them, so when i run the system manager, under i will see and manage both servers (the standard and the enterprise).

Thank you very much

Rezuma