Windows Vista, ODBC and SQL Server 2005
The following has also been added to the Access Performance FAQ page.
For the best connection string for a DSN-less connection to SQL Server 2005, switch providers to the SQL Native Client with the following:
"ODBC;Driver={SQL Native Client};Server=<servername>;DATABASE=mydatabase;Trusted_Connection=Yes"
by Rick Byham of Microsoft. See the thread Vista, ODBC and SQL Server 2005