Outlook 200 acessing foreign Exchange

[Simon]

I have winxp clients logging onto a non exchange aware AD
I have outlook 200 clients on the same network but behind
a firewall to the remote AD with exchange 2000
now can I simply enable static ports on the exchange
server to get thru the firewall
or should i also do the same with local AD/DC's to the
exchange server for the GC service?
I've tried scanning technet with out a firm position.

many thanks in advance