Our SAP core systems are running Windows 2003/SQL 2005 x64, all VM's on esxi 5.1 hosts. I want to migrate as much for the OS as for SQL. Having the ability to upgrade memory and processors on VM's without rebooting is not possible on Windows 2003 OS. This feature comes in handy when extra horsepower is temporarily needed in special situations. MIgrating is a pain and I don't want to do it again soon. So I plan to migrate both OS and SQL to Windows 2012/SQL 2012. I would rather go a little more pain on this migration than have to do it again soon.