If you are working with W7 64bit, and go to
Control Panel -> Administrative tools,-> Data Sources (ODBC)
The ODBC Data Source Administator Window will pop up.
This is actually pointing to this .exe file "C:\Windows\System32\odbcad32.exe"
If you try to Add a new ODBC data source
only the SQL Server driver will show up.
To sort this problem you need to load up the 32bit version of this Window that can be found at the following path.
This way you can create DSN connection other than SQL Server on a 64bit OS.
For futher details just go here