We have 2 domain controllers running at window server 2003 32-bit. Our old exchange server is also at server 2003 32-bit. Since Exchange 2007 wont work with 32 bit therefore I plan to install it on new server (Windows server 2008 64-bit). Since the DCs are at 32-bit while Exchange server at 64-bit. Do I have to do any extra step? Another question. Is there any place for me to download full exchange 2007 with SP1 on it? I have the Exchange 2007 RTM DVD but it wont work with Server 2008. I know that the product key or licensing should be no problem with that but I want to know the place to download it. I check the link below but it only have 1.6GB therefore I'm not quite sure whether it a full version or not. http://www.microsoft.com/downloads/details.aspx?FamilyId=44C66AD6-F185-4A1D-A9AB-473C1188954C&displaylang=en Thank you very much. enz

No ENZ, you dont have to perform any additional steps during Exchange implementation. For additional reading, you can see the recommendation about AD servers in below article, the recommended ratio of ActiveDirectory directory server processor cores to Exchange2007 Mailbox server processor cores is 1:4 for 32 bit and 1:8 for 64 bit. Exchange 2007 System Requirements http://technet.microsoft.com/en-us/library/aa996719.aspx About second question, yes it is full version of Exchange and you need to enter product key to activate it.

Thanks Amit. Very clear explaination.