If you’re trying to install vSphere onto an x64 Windows server, you might have hit a snag where the installation requests the creation of a 32-bit Data Source Name (DSN) for its database. If you’re attempting to create that DSN through the “regular” Data Sources (ODBC) administrative tool, you’re going to have a problem.
The “regular” ODBC console only has the capability of creating system DSNs that are used by x64 processes. What you need is the “other” ODBC console that works for x86.
You can find it at: %systemdrive%\Windows\SysWoW64\Odbcad32.exe
You will also need the SQL Native Client, which you can download from http://go.microsoft.com/fwlink/?LinkId=123718&clcid=0x409.
More information about this problem can be found in VMware’s ESX 4.0 and vCenter Server 4.0 documentation here.
Get more great virtualization tips, just like this one at http://windowsitpro.com/go/gregshieldsvirtualization.