When installing vCenter on Windows 2008 R2 and you’re planning to connect to a Windows 2008 SQL server you must use a 32 bit ODBC DNS. This is old news for the most of us. But When your planning to use the Windows 2008 (R2) as the platform for vCenter you must first install the Microsoft SQL Server 2008 Native Client on the server or else there is no Native client visibly in het selection menu form ODBC.This dynamic-link library is not default present on your system en must be installed separately.
So download the Microsoft SQL Server 2008 Native Client for W2008 or W2008R2. Watch out read the page carefully because there are a lot of download links on them. You must have the Microsoft SQL Server 2008 Native Client. install this on the system you plan to use for vCenter. Go to %systemdrive%SysWOW64odbcad32.exe and make you’re 32 bit DNS in the System DNS tab. For more information see ICT Freak