Scenario: I want to move vCenter DB from the bundled SQL 2005 express to a standalone SQL 2008. The SQL Native Client required for the upgrade is 10.0
To check what version you have running (on SQL 2005):
Run regedit -> Computer->HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Microsoft SQL Native Client/Current Version.
As you see from the screenshot I am currently running 9.0.x so I will need to upgrade this during the migration
This is slightly different in SQL 2008 but same principles apply.