NT4.0 --> Active Directory

Dear all

We want to install the latest Enterprise Portal and use the integrated functionality to connect other SAP Systems like e.g. BW.

Unfortunately our system landscape is quite old:

Domaincontroller runs on NT 4.0

Exchange 5.5

R/3 4.6C

BW 3.0B

Are there any restrictions regarding the above mentioned system connectivity within the portal (e.g. issues about SSO) or any other restrictions caused by the fact that Active Directory has not been set up so far?

What would happen if we install the EP on the actual System Landscape and would go for AD later? What would we have to do in this case and how much would the effort be?

Your opinion is appreciated very much.

Thank you