When to use the SQL Native Client
The SQL Native Client should only be used in certain contexts. This is the definition of when to use it, and when not to
.Net applications
Do not use the SQL Native Client for .Net applications. Instead use the .NET Framework Data Provider for SQL Server (SqlConnection).
COM and all other then .Net applications
Use the SQL Native Client if you are accessing an SQL Server 2005 and need the new features of SQL Server 2005 such as MARS, encryption, XML data type etc.
Continue use your current provider (OLE DB / ODBC through the MDAC package) if you are not connecting to an SQL Server 2005 or if you are connecting to an SQL Server 2005 but are not using any of the new SQL Server 2005 features.
Summary
OLE DB and ODBC does not support some of the new features in SQL Server 2005 and above. The managed .Net providers does. The SQL Native Client can be seen as a solution to have access to the new SQL Server features from native (non .Net) code. There are no other benefits from using it.
