> Some advice about this ?
I would recommend to upgrade to Small Business Server 2003, it includes
Exchange 2003 and is relatively cheap. As a bonus you get an intranet,
monitoring, reporting, remote web workplace, VPN and great management with
the wizards and high level of integration.
Or do you require Exchange 2007 stuff like Unified Messaging? I'm not aware
of best practices or specific problems. This setup is often used for testing
and lab purposes and I have not experienced any problems. Of course you
can't use other DC and GC for load balancing and fall back.

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Jetze Mellema (MS MVP)
Lees mijn blog: http://jetzemellema.blogspot.com/
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How to ask a question: http://support.microsoft.com/?id=555375
Jetze Mellema (MS MVP) - 20 Feb 2008 15:17 GMT
> I'm not aware of best practices or specific problems. This setup is often
> used for testing
Now I am. :-)
Please see
http://technet.microsoft.com/en-us/library/aa996719(EXCHG.80).aspx
"Installing Exchange 2007 on Directory Servers
For security and performance reasons, we recommend that you install Exchange
2007 only on member servers, and not on Active Directory directory servers.
Although installing Exchange 2007 on a directory server is supported, it is
strongly discouraged. However, you cannot run DCPromo on a computer running
Exchange 2007. After Exchange 2007 is installed, changing its role from a
member server to a directory server, or vice versa, is not supported.
If you install Exchange 2007 on a global catalog server, and if you restart
the server, you may need to start the required Exchange services manually.
For more information, see Knowledge Base article 940845, Exchange 2007
services cannot start automatically after you install Exchange 2007 on a
global catalog server.
(http://go.microsoft.com/fwlink/?LinkId=3052&kbid=940845)"

Signature
Met vriendelijke groet,
Jetze Mellema (MS MVP)
Lees mijn blog: http://jetzemellema.blogspot.com/
Mijn hobby: http://www.mellema.net/homecomputers
How to ask a question: http://support.microsoft.com/?id=555375