Understanding Kerberos and NTLM authentication in SQL Server Connections

http://blogs.msdn.com/b/sql_protocols/archive/2006/12/02/understanding-kerberos-and-ntlm-authentication-in-sql-server-connections.aspx

SQL Linked Server Query failed with “Login failed for user …"

http://blogs.msdn.com/b/sql_protocols/archive/2006/08/10/694657.aspx