Kerberos issue on SQL 2005

After some searching i've managed to add "read/write servicePrincipalName" access for a "domain account" with ADSIEdit.
After restarting the SQLServer Service, the eventlog shows it is listening on a specific dynamic port. Again back in ADSIEdit I see, I believe, the appropriate "service principle name". Even after removing and restarting the SQL Server, the same SPN is written back here.
Even then, in sql server, the command "select auth_scheme from sys.dm_exec_connections where session_id=@@spid" still shows NTLM instead of Kerberos. Using SETSPN -L <domain account> results in a line like MSSQLSvc/

How come SQLServer is showing using NTLM instead of Kerberos?
Does a client which uses Kerberos also trigger SQL Server to start using Kerberos?

Thanks for your reply.