Currently KB 1022104 states the following: 1.     Make sure your database requirements and patch levels are compliant: Note: For more information, see vSphere Compatibility Matrix and vCenter Server Database Patch and Configuration Requirements. To use an existing database, you will need to provide a 64 bit system DSN which points to the vCenter Server database. [...]

Companies running VMware have already achieved enormous gains through virtualization. The next wave of benefits will come when they reduce the time and effort required to run and manage VMware platforms. The VMware Infrastructure Software Development Kit (VI SDK) includes application programming interfaces (APIs) that allow developers and administrators to do just that. Until now, [...]

When you get around to installing vSphere,  if on a 64-bit Windows host in x86 compatibility mode, a 32-bit DSN is required for the database connection. If a DSN has been set up through Start > Administrative Tools > Data Sources (ODBC) the vSphere installer won’t be able to use this DSN. The 64-bit ODBC [...]