We, have an Exchange infrastructure that includes both a front-end and backend Exchange 2007 server environment. It has approximately 50 to 75 mailboxes and is a single site server running as a member server. Can anyone give me a rough estimate in terms of time it will take to upgrade/migrate Exchange 2007 to Exchange 2010? Not including the time it may take if there are additional problems ie:troubleshooting but take a stab at that estimate separately. I just need a rough estimate.