From a Jonathan Monroe suggestion I posted this comment few minutes ago, but it’s very important so it deserves a separated post:
In order to use ODBC with a 32-bit application (such as MS Office) on 64-bit Windows, you have to install the 32-bit driver. In order to configure a DSN for the 32-bit driver, you have to use the 32-bit ODBC Administrator, located at:
A DSN configured using the default 64-bit ODBC Administrator will not be recognized by 32-bit applications. More information about this situation is available here:
It is important to understand that you have to use the 32-bit ODBC Administrator on 64-bit Windows if you want to use the driver with MS Office or any other 32-bit application.