This question has come up lots of times and the general statement is that it is not trivial. In fact the normal question is can Exchange 2007 be run on an SBS 2003 box. The answer to this is a resounding NO. Exchange 2007 is 64-bit and SBS 2003 is 32-bit and never the twain shall meet. The closest you can get is installing a Windows Server 2003 64-bit system and putting Exchange on it. You will have to buy a Windows Server license, Exchange 2007 license and CALs for each client that uses it. (note if you want Outlook Voice Access then you need Enterprise CALs even if you are only installing Exchange 2007 Standard edition). Once this is done you need to decide if you are going to keep your Exchange 2003 box or forward ports to the new system. If you are keeping both then you also need to be aware of (note this comes from an e-mail from Karan in our support team and should not be considered complete, but a pointer in the right direction): Please note that Exchange 2007 would appear in a different administrative...