Exchange 2003 Transition to Exchange 2013

This post will be updated as time passes and I continue working on this project.
I am setting up a virtual lab to replicate an existing environment which contains Server 2003 Domain Controller/DNS/DHCP and Server 2003 with Exchange 2003.
The goal is to determine the best possible path to transition from Exchange 2003 to Exchange 2013.  The two scenarios I know are an initial transition from Exchange 2003 to Exchange 2010 and then from Exchange 2010 to Exchange 2013.  The other option would be to export individual user mailboxes into PST and import into Exchange 2013.

Phase 1

I will setup a 2008 R2 virtual server to install a 180 day trial of Exchange 2010 and put it into this VM lab environment to start the transition process.  Afterward, remove Exchange 2003 from the domain completely.
Next will be totransition from Exchange 2010 to Exchange 2013 and remove Exchange 2010 from the domain completely.

• Setup Windows 2003 Domain
• Setup Windows 2003 + Exchange 2003
• Install 2008 R2 SP1
• Install and run Exchange Pre-Deployment Analyzer (2010) (Link)
  • 
  • Raise domain functional level to 2003 native
  • Raise forest functional level to 2003 native
  • Modify Exchange 2003 server and add Registry Key HKLMSystemCurrentControlSetServicesRESvcParameters adding SuppressStateChanges DWORD with value of 1
  • Install .NET 3.5 on 2008 R2 SP1 server for Exchange 2010 pre-requisite
• Install Exchange 2010 SP3
  • Run setup with the following switches
    • setup.com /PrepareLegacyExchangePermissions
    • setup.com /PrepareSchema
    • setup.com /PrepareAD
    • setup.com /PrepareDomain
  • Start Graphical Setup (setup.exe)
    • 
• Determine Transition Path from 2003 to 2010 Exchange

Phase 2

Export mailboxes from users.  Remove Exchange 2003 from the domain.  Setup Server 2008 R2 and install Exchange 2013 in the domain.  This phase should be fun.