I've got a machine set up and running 2k8 32 bit windows server. Cost aside, which set up would be better.Risk formatting my 2k8 windows server(downtime) and installing 64 bit windows server then install exchange 2k7.Or would it be better (remember, cost aside) to buy a comparable box with with Windows Server 2008 64 bit and exchange 2k7 and run it as a dedicated machine, secondary to the windows 2k8 32 bit active directory controller.Are there any major flaws with this set up or will it just be some configuration head aches?I'd appreciate any advice and remember, we are more concerned with minimizing risk and downtime than a few grand. Thanks!

Exchange 2007 32 bit is not supported in production environment. If you are talking that Exchange & DC both are on same machine then it would be highly recommended to keep a dedicated Exchange 2007 server, reason is DC is already loaded with its own functionality and if you put Exchange 2007 in it then it may die if it doesnt have enough resource, however recovery would be very difficult or not possible if it crashes. References of Exchange 2007 on Windows 2008 Exchange Server and Windows Server 2008 Exchange Server and Windows Server 2008, Part II