I just upgraded to 64-bit Windows 7 (which I really like) and have had very few problems until I tried to configure data merge. When I went to Control Panels -> Administrative Tools -> Data Sources (ODBC) to setup a System DNS for Excel, all that was available was the SQL Server driver.
After much searching I found (on the SQL Server Developer Center of all places) that there is a 32-bit ODBC Administrator with all the drivers I'm familiar with. Instead of going to Control Panel..., run %WINDIR%\SYSWOW64\ odbcad32.exe
