PowerDesigner is only available in a 32-bit version, but installation on 64-bit versions of Windows is supported.
To ensure that PowerDesigner can communicate with your data sources, you should use the 32-bit version of the ODBC Administrator tool. PowerDesigner cannot connect to 64-bit ODBC DSNs. For detailed information about working with 32-bit DSNs on a 64-bit version of Windows, see http://support.microsoft.com/kb/942976.