Can I install Exchange 2013 in a Exchange 2007 SP3 (2008 DFL/FFL) environment, if I set the virtual directories properly? I'd like that to be the first step and then install Exchange 2013 and configure mail to flow through there the next day. I understand the DNS and Cert (legacy, mail, autodiscover) requirements. Plan is to set the DNS up, all pointing to 07, then the next day install and setup 13. Then setup the virtual directories and DNS to allow for 13 to proxy to 07. Would that work out smoothly with no impact to my users (local/remote)?