Jeff Middleton is founder of IT Pro Experts and creator of the Swing Migration methodology and tool kit. He has just announced new updates to his kits.
http://itproexperts.com/blog/platform-migration-project-solutions-matrix/
I have successfully used Jeff’s Swing Migration for years to upgrade customers from older versions of SBS to the newer Microsoft platforms (SBS 2008, SBS 2011, Windows Server Essentials 2012). His methodology also applies to standard Windows and Exchange server migrations.