Datasheet View of list/library not supported when 64 bit of Office 2010 is used

By default, the Datasheet view of a list or library is not supported when you are using the 64-bit version of Microsoft Office 2010 installed on a 64-bit Windows operating system.

In order for Datasheet view to work download Data Connectivity Components driver.  These components are available on the Microsoft download center:
2007 Office System Driver: Data Connectivity Components